Answer:
x=6
Explanation:
we know that the area you are trying to solve for has to be equal to 90 degrees. so you would add the two equations together 5x and (x+54).
STEP ONE
combine like terms and get 6x+54=90
STEP TWO
move get 6x to the right hand side and change the sign, 6x=90-54
STEP THREE
subtract the numbers, 6x=36
STEP FOUR
divide both sides of the equation by 6, x=6