Question

I opened a grocery account at my bank with $100. Every week thereafter, I withdraw $45 from the account to pay for groceries. If x is the number of weeks I've had the account, then y is the amount in the account. Find an equation of a line in the form y = mx + b that describes my grocery account balance.

Answer 1

y=-45x + 100

Explanation:

The slope-intercept form is y=mx+b where m is the slope and b is the y-intercept or in other words the initial amount (when x is 0). Since you start off with 100 dollars the y-intercept is going to be 100 since after 0 weeks (when you opened the account) you put 100 dollars in... so you should have 100 dollars. The slope is going to be -45 since you are withdrawing 45 each week so the value is going to be decreasing by 45 every week. If you put that together you get y=-45x+100