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 to lay after d days is given by the following function
L(d)=140-5d
Answer the following question
A)how many miles of track does the crew have left to lay after 18 days
_______miles
B)how many days will it take the crew to lay all the track
______days
A) After 18 days, the crew has left to lay L(18) miles of track.
L(18) = 140 - 5(18)
L(18) = 140 - 90
L(18) = 50
So, the crew has left to lay 50 miles of track after 18 days.
B) To find out how many days it will take the crew to lay all the track, we need to solve the equation L(d) = 0.
L(d) = 140 - 5d
0 = 140 - 5d
5d = 140
d = 140/5
d = 28
Therefore, it will take the crew 28 days to lay all the track.