reliable taxis : for 30 miles
C = 1.5x....x = 30
C = 1.5(30)
C = 45
speedy taxis : for 30 miles
C = 1.1x + 11.5....x = 30
C = 1.1(30) + 11.5
C = 33 + 11.5
C = 44.5
city taxis : for 30 miles
C = 1.25x + 8...x = 30
C = 1.25(30) + 8
C = 37.5 + 8
C = 45.5
the cheapest company is : speedy taxis