Inspired by her new love of math developed in Bridge to College Math, Susan decides to open a math tutoring center. She found a nice office that she can lease for $400 per month. Susan is going to charge $25 per hour for her tutoring service.
She is examining her monthly budget.

a) Write an equation using function notation to model Susan's monthly income (I) as a function of the numbers of hours (x)
she spends tutoring in one month.
Function: