The area of a triangle varies jointly as its base and altitude. By what percent will the area change if the base is increased by 15% and the altitude decreased by 25%?

Answer 1

A1 = 0.5bh,

A2 = 1.15*0.5b*1.25h = 0.71875bh.

A2 / A1 = 0.71875bh / 0.5bh = 1.4375 =
143.75%.

% Change = 143.75 - 100 = 43.75.