The cheese that ms. carter used to buy costs $6.00 per pound, but it's been marked up 15%. how much does it costs to buy 2.6 pounds of cheese at the new price?

So, we have to first find what it costs. There is a trick with mark ups, and we will use both ways to solve it.
1st way:
6×1.15= 6.90
2nd way:
6×.15=.9+6=6.90
So it will now cost 6.90 per pound, now let's see how much for 2.6 pound.
6.9×2.6=17.94.
It will cost $17.94 for 2.6 pounds of cheese.

First subtract 10 from both side
y^2+6y-16=0
(y+8)(y-2)=0
-8 and 2