#### Answer

Total costs will be equal when the bus is used
30 times in a month

#### Work Step by Step

Let x = number of times a bus is used.
At no discount, total cost = $1.25x$
With the discount, total cost = $0.75x+15$
To find when the total costs will be equal, solve
$ 1.25x=0.75x+15\qquad$ ... subtract $0.75x$
$ 0.5x=15\qquad$ ... multiply with 2
$x=30$
Total costs will be equal when the bus is used
30 times in a month