Question

noah has 9 grapes that he took from diego. noah then decides to give 4 back.
part a: write a subtraction expression to describe how many grapes noah has.
part b: write the subtraction expression as addition.
part c: what is the change in the number of grapes noah has?

Explanation:

Part A

Step1: Identify initial and given-back grapes

Noah starts with 9 grapes, gives back 4. So the subtraction expression is initial minus given back.
$9 - 4$

Step1: Recall subtraction as addition of opposite

Subtracting a number is adding its opposite. So $9 - 4 = 9 + (-4)$.
$9 + (-4)$

Step1: Calculate the subtraction

First, do $9 - 4 = 5$. The initial was 9, final is 5. The change is final - initial? Wait, no: initial is 9 (after taking), then gives back 4, so change is (9 - 4) - 9? Wait, no. Wait, Noah took 9 (so his grapes went from, say, 0 to 9), then gave back 4, so his grapes are 9 - 4 = 5. The change from when he took (9) to after giving back is 5 - 9? No, wait the question is "change in the number of grapes Noah has" – from the start (before taking) or after taking? Wait, the problem says "Noah has 9 grapes that he took from Diego" – so initially (after taking) he has 9, then gives back 4, so the change is 9 - 4 - 9? No, no. Wait, the change is the difference between the final and the initial (after taking). So initial (after taking) is 9, final is 9 - 4 = 5. So change is 5 - 9 = -4? Wait, no, maybe the change from before taking? Wait, no, the problem says "Noah has 9 grapes that he took from Diego" – so he took 9 (so his grapes increased by 9), then gave back 4 (decreased by 4). But the question is "change in the number of grapes Noah has" – probably from when he had 9 (after taking) to after giving back. So 9 - 4 = 5, so the change is 5 - 9 = -4? Wait, no, maybe I misread. Wait, the problem: Noah has 9 (after taking), then gives 4 back. So the number of grapes he has changes from 9 to 9 - 4 = 5. So the change is 5 - 9 = -4? But that seems odd. Wait, maybe the change is the amount he gave back? No, let's calculate 9 - 4 = 5. So he had 9, now has 5. The change is 5 - 9 = -4, meaning a decrease of 4. But maybe the question is simpler: 9 - 4 = 5, so the change is -4 (if we consider the initial as 9) or +5 - 9? Wait, no, let's do the math: 9 (initial after taking) minus 4 (given back) is 5. So the change in his grapes (from when he had 9 to after giving back) is 5 - 9 = -4. But maybe the question is asking for the result of 9 - 4, but no, "change" is the difference. Wait, maybe I made a mistake. Wait, the problem says "What is the change in the number of grapes Noah has?" – so he had 9, now has 9 - 4 = 5. So the change is 5 - 9 = -4? But that's a decrease of 4. Alternatively, maybe the change from before taking: he took 9 (so +9), then gave back 4 ( -4), so total change is -4. But let's check the calculation: 9 - 4 = 5. So if he had 9, now has 5, the change is 5 - 9 = -4. But maybe the question is just asking for 9 - 4 = 5, but that's the final number, not the change. Wait, no, "change" is final - initial. Initial (after taking) is 9, final is 5. So change is 5 - 9 = -4. But maybe the problem means the change from when he had 0 (before taking) to after giving back: he took 9 (change +9), then gave back 4 (change -4), so net change is +9 -4 = +5? No, that's confusing. Wait, let's re-express:

Noah's grape count:

• After taking from Diego: 9 (let's say this is time 1)

• After giving 4 back: 9 - 4 = 5 (time 2)

Change in grape count from time 1 to time 2: 5 - 9 = -4.

But maybe the question is simpler: the change is the amount he gave back, but no. Wait, maybe the question is asking for the result of 9 - 4, but that's 5, but that's the final number, not the change. Wait, the problem says "change in the number of grapes Noah has" – so from time 1 (9) to time 2 (5), the change is -4. But let's calculate 9 - 4 = 5, so the number of grapes he has changed by -4 (decreased by 4) from when he had 9. But maybe the question is just asking for 9 - 4 = 5, but that's the final count. Wait, no, the question is "change", so it's final - initial. Initial (after taking) is 9, final is 5, so 5 - 9 = -4. But maybe I'm overcom…

Answer:

$9 - 4$

Part B