The costs are equal when the bus is used 30 times.
Work Step by Step
Let x = number of rides on a bus in a month. Cost of bus fare, no discount = $1.25x $ Cost using a pass, with discount = $15+0.75x $ We want the x for which these two costs are equal. $1.25x $=$15+0.75x \qquad $ ... add $-0.75x $ $0.5x=15 \qquad $ ... multiply with 2 $ x=30.$ The costs are equal when the bus is used 30 times.