Question

Shawna has $100 in the bank. She deposits $5 each week. Ruben has $75 in the bank. He deposits $20 every Monday, and he spends $10 each week. After how many weeks will they have the same amount in the bank? Show or explain how you got your answer.

Answer 1

Set up 2 equations, with x being the number of weeks:

Shawna = 100 + 5x

Ruben = 75 + 10x ( Use 10 because although he deposits 20 he uses 10, so every week his account only increases by 10).

Set the equations equal to each other and solve for x:

100 + 5x = 75 + 10x

Subtract 5x from both sides:

100 = 75 + 5x

Subtract 75 from both sides:

25 = 5x

Divide both sides by 5:

x = 25/5

X = 5

It will take 5 weeks.