Question

A railroad crew can lay 7 miles of track each day. They need to lay 189 miles of track. The length, L (in miles), that is left to lay after d days is given by the following function.=L(d)=189-7dAnswer the following questions.(a)How many days will it take the crew to lay all the track?days(b)How many miles of track does the crew have left to lay after 17 days?miles

Answer 1

ANSWER :

a. 27 days

b. 70 miles

EXPLANATION :

From the problem, we have the function :

$L(d)=189-7d$

a. The number of days will it take the crew to lay all the track is the value of d when L(d) = 0

That will be :

$\begin{gathered} 0=189-7d \\ 7d=189 \\ d=\frac{189}{7}=27 \end{gathered}$

b. After 17 days, d = 17 the length of the track left is :

$\begin{gathered} L(d)=189-7d \\ L(17)=189-7(17) \\ L(17)=70 \end{gathered}$