Jonah received $300 in cash gifts for his fourteenth birthday. the function y remaining after x week if Jonah spends $25 each week. Graph the function and determine the amount remaining after 9 week

Assume that y its Jonah's cash and its initially 3000

y=300

But he spends 25/week. Assume that x is number of weeks.

y=300-25*x - its our function

If we want to find Jonahs cash after 9 week we have to substitute x=9, so

y=300-25*9

y=300-225

y=75$ - its the result