7 weeks
Explanation
Step1
initial balance= +400
she wants to have at least 210
Let
x represents the number of weeks she can take out $25
Step 2
make the equation
210 in the account by the end of the summer = initial balance -money she spent x weeks
[tex]210=400-25x[/tex]Step 3
solve for x
[tex]\begin{gathered} 210=400-25x \\ \text{subtract 400 in both sides} \\ 210-400=400-25x-400 \\ -190=-25x \\ \text{divide both sides by -25} \\ \frac{-190}{-25}=\frac{-25x}{-25} \\ x=7.6 \end{gathered}[/tex]7.6 weeks, then she can take out 7 weeks.
I hope this helps you
