Get photomath :) it'll give you the answer automatically.
The formula you can use for this is y=2/3×-5
Where the y is the cost of cats food and x is the cost of the dogs food
From the text you can derive the following equations:
(1) A = bh/2 = 8
(2) and h = b+6
Fill in h in (1):
b(b+6)/2 = 8 => b^2 + 6b = 16 with the quadratic formula or simply trying some values for b you can find b=2, so h=8.