Heather has $500 in her savings account. She withdraws $20 per week for gas. Write an equation Heather can use to see how many weeks it will take her to have a balance of $220

Accepted Solution

Since she has a base amount of $500, that will be your y-intercept. 20 is going to be your slope, and since she's withdrawing it, it will be -20. Here's how the equation would be set up (in y = mx + b):

-20x + 500 = 220

*Subtract 500 from both sides*

-20x = -280

*Divide both sides by -20*

x = 14.

Therefore, it will take 14 weeks.