X = - 4
2(-4-8) = -4 + 5(-4)
I seem to have read the question wrong.
Answer:
$405.4
Step-by-step explanation:

-->180*(1+7/100)^12
-->$405.4
Let's set up a formula for this, where x is the amount of dvds he started with:
x-45+10=15
x-35=15
+35 +35
x=50
He had 50 DVDs to begin with.
Check
50-45+10
=15