Problem: Airplane seats.
An airplane has a total of 152 seats. The number of coach-class
seats is 5 more than six times the number of first-class seats.
How many of each type of seats are there on the plane?
C = 6F + 5
C + F = 152
(6F + 5) + F = 152
7F + 5 = 152
7F = 147
F = 21
C = 6F + 5
C = 6*21 + 5
C = 126 + 5
C = 131
There are 21 first-class seats and 131 coach-class seats.