a railroad crew can lay 5 miles of track each day. they need to lay 145 miles of track. how many days will it take? and how many miles of track does the crew have left after 19 days

Answer:
29days
Explanations
Given the equation for the length of the railroad after d days expressed as;
L(d) = 145 - 5d
a) If a railroad crew can lay 5 miles of track each day, then;
5 miles = 1 day
To get the number of days needed to lay all the tracks;
145 miles = x day
Divide both expressions
5/145 = 1/x
Cross multiply
5x = 145
x = 145/5
x = 29days
Hence it will take 29days to lay all the tracks