A railroad crew can lay 7 miles of track each day. They need to lay 203 miles of track. The length, L (in miles), that is left to lay after d days is given by the
following function.
L(d) = 203 - 7d​
(How many days will it take the crew to lay all the track?)
(How many miles of track does the crew have left to lay after 18 days?)