Answer:
$8
Explanation:
Let x represent the amount of money he has to save each week.
We can use this to set up an equation:

Now, we have to "isolate the variable". This means we must have a resulting equation of
.
In this case, we can use the Division Property of Equality to divide both sides by 7:

Therefore he must say $8 each week for 7 weeks so that he can buy the guitar.