Joe opens a bank account that starts with $20 and deposits $10 each week. Bria has a different accou

Joe opens a bank account that starts with $20 and deposits $10 each week. Bria has a different account that starts with $1000 but withdraws $15 each week. When will Joe and Bria have the same amount of money?

Let w be the number of weeks. Deposits mean we add money and withdrawals mean we subtract money.

Joe's Balance function B(w) where w is the number of weeks:
20 + 10w

Bria's Balance function B(w) where w is the number of weeks:
1000 - 15w

The problem asks for when both balances will be the same. So we set them equal to each other and solve for w:
20 + 10w = 1000 - 15w

To solve for w, we type this equation into our search engine and we get:
w = 39.2

We round up to full week and get:
w = 40