Question

a railroad crew can lay 5 miles of track each day. they need to lay 140 miles of track. the length, l (in miles), that is left to lay after d days is given by the following function.
l(d) = 140 - 5d
answer the following questions.
(a) how many miles of track does the crew have left to lay after 17 days?
miles
(b) how many days will it take the crew to lay all the track?
days

Explanation:

Part (a)

Step 1: Identify the function and input

We have the function \( L(d) = 140 - 5d \), and we need to find \( L(17) \), so we substitute \( d = 17 \) into the function.

Step 2: Substitute and calculate

$$
LATEXBLOCK0
$$

Part (b)

Step 1: Set up the equation

When all the track is laid, \( L(d)=0 \). So we set \( 140 - 5d = 0 \).

Step 2: Solve for \( d \)

$$
LATEXBLOCK1
$$

Answer:

(a) 55 miles
(b) 28 days