## Thinking Mathematically (6th Edition)

Consider the equation for the condition at which the bus fare with discount pass is equal to the bus fare without discount $1.25x=15+0.75x$ Here, x is the number of times in a month the bus must be used Now, solve the above equation \begin{align} & 1.25x=15+0.75x \\ & 1.25x-0.75x=15 \\ & 0.5x=15 \\ & x=30 \end{align} Thus, the number of times the bus must be used in a month is 30.