Question

You have $30 dollars saved up. Every week you spend $6 at the arcade. Write an equation in slope intercept form that shows how much money you have (y) after x weeks.

Answer 1

y = -6x + 30

Explanation:

The inicial value you have is $30, so this will be the value of y after 0 weeks, that is, x = 0

After one week, you spend $6, so you will have y = 30 - 6 = 24 when x = 1.

With these pair of values, we can find the linear equation:

y = ax + b

for x = 0, y = 30:

30 = a*0 + b

b = 30

for x = 1, y = 24:

24 = a*1 + 30

a = 24 - 30 = -6

So, our equation is:

y = -6x + 30