Question

self test
evaluate using the order of operations (pemdas):
1.) $2 \cdot 5 - 3 \cdot 5 =$
2.) $-25 \div 5 - 8 =$
3.) $-10 \div 2 \cdot 8 - 4 =$
4.) $2(3 - 5) \cdot (4 - 1) =$

evaluate by substituting the given value of each variable.
5.) $2x + 3$ if $x = -2$
6.) $5 - 3x$ if $x = -2$
7.) $-4ab$ if $a = 2$, and $b = -1$
8.) $3x + 4 - 8y$ if $x = -3$ and $y = 1$

simplify by combining like terms.
9.) $-2a + (-3a) =$
10.) $3x + (-10x) =$
11.) $-8z - (-7z) =$
12.) $3x + 4 + (-6x) + -3 =$
13.) $5x - 7x =$
14.) $7x - 3y - 9x - 4y =$
15.) $-3x + 4 - x - 9 =$

multiply.
16.) $(3x)(-8y) =$
17.) $-3(-2ab) =$

divide.
18.) $\frac{-60a}{20} =$
19.) $\frac{-18xy}{-6} =$
20.) $\frac{28x}{-7} =$

Explanation:

Problem 1: \( 2 \cdot 5 - 3 \cdot 5 \)

Step 1: Perform multiplications

First, calculate the multiplications: \( 2 \cdot 5 = 10 \) and \( 3 \cdot 5 = 15 \).

Step 2: Perform subtraction

Then subtract the results: \( 10 - 15 = -5 \).

Step 1: Perform division

First, do the division: \( -25 \div 5 = -5 \).

Step 2: Perform subtraction

Then subtract 8: \( -5 - 8 = -13 \).

Step 1: Perform division

First, divide: \( -10 \div 2 = -5 \).

Step 2: Perform multiplication

Then multiply by 8: \( -5 \cdot 8 = -40 \).

Step 3: Perform subtraction

Subtract 4: \( -40 - 4 = -44 \).

Answer:

\( -5 \)

Problem 2: \( -25 \div 5 - 8 \)