The cost 

c (in dollars) for the fuel and maintenance of a go-cart is given by
c=10x+1200
c=10x+1200
, where x is the number of rides. It costs $40 per ride. How many rides does it take to break even?

40

40

The answer is truly 40 rides

c = 10x + 1200 = 40x. X = 40 rides.

The cost cc (in dollars) for the fuel and maintenance of a go-cart is given by c=9x+1500c=9x+1500, where xx is the number of rides. It costs $34 per ride. How many rides does it take to break even?

25

Actually it's 60.