Math Equation Anyone...?

Question

ok i have the answer but i dont know how to set this problem up into an equation.

the bust fare in a city is 1.25. ppl who use the bus have the option of purchasing a monthly coupon book of 15.00. w/the book the fare is reduced to .75. determine the number of times in a month the bus must be used so that the total montly cost w.out the coupon book is the same as the total monthly cost with the coupon book.

Answer 1

Let's say X = number of bus trips.

1.25X is the amount of money you would spend taking X trips without the coupon book.

With the coupon book, you have the pay $15 up front, and then .75 per trip, so that would be 15 + .75X.

Just set those equal to each other and solve for X.

1.25X = 15 + .75X

Subtract .75X from both sides:

.5X = 15

Divide both sides by .5:

x = 30