1.
Part A.
bh + hr = 25
h( b + r ) = 25
h = 25/ b + r
Part B
hr = 25 - bh
r = (25 - bh)/h
r = 25/h - b
2.
Part A.
xy = r - h
-h = -r + xy
divide both sides by -1
h = r - xy
Part B
xy = r - h
xy + h = r
r = xy + h
3.
4x - 2y = 8
-2y = 8 - 4x
divide through by -2
y = 8/-2- 4x/-2
y = -4 + 2x
therefore Camille solved the equation correctly
4.