I think this is the problem. 7% and 8% do not equal 7 and 8. Try plugging in .07x + .08y
Your answer should be 15000. Don't hold me accountable, though.
My last problem I'm going to ask help with for today at least.
I set it up as follows:
0x+1y = -235470
That just doesn't seem right, a person being in the whole for way more than they invested.