A railroad crew can lay 7 miles of track each day. They need to lay 196 miles of track. The length, L (in miles), that is left to lay after d days is given by the following function.
(a) How many miles of the track does the crew has left to lay after 18 days?
(b) How many days will it take the crew to lay all the track?
To solve part (a): replace d with the value 18 and finish: L(d) = 196 - 7 · 18 [finish this]
To solve part (b): replace L(d) with 0 and solve for d: 0 = 196 - 7d [finish this]
another unrelated question has been deleted. (Melody)