solution:
One leg of the triangle is given 90ft. the other leg of the triangle is x, and the hypotenuse is given as x+30
According to Pythagoras,
C² = a² + b²
So,
(x +30) = x² + 90²
Use FOIL to expand the binomial:
x² + 60x + 900 = x² + 8100
60x = 7200
X = 7200/60
X = 120