Question

You have ​$85 in your bank account. Each week you plan to deposit ​$7 from your allowance and ​$15 from your paycheck. The equation b=85+​(15+7​)w gives the amount b in your account after w weeks. How many weeks from now will you have ​$210 in your bank​ account?

Answer 1

6 weeks

Explanation:

So the amount b we will have in our account w weeks from now is given by the equation:

`b=85+(15+7)w`

To find out after how many weeks from now we will have $210, substitute 210 for b and solve for w:

`210=85+(15+7)w`

Subtract 85 from both sides:

`125=(15+7)w`

Add within the parentheses:

`125=22w`

Divide both sides by 22:

`w=125/22\approx5.68\approx6`

In other words, we will have $210 after approximately 6 weeks.