Let the base angle be x. If the obtuse angle is two and a half times the base angle, it will be 2.5x. In a triangle, all three angles will add up to 180. The third angle, the other base angle will be equal to x. So the equation will be:
x + x + 2.5x = 180 2x + 2.5x = 180 4.5x = 180 x = 40
Writing an equation is the easiest way to figure this out. b = boys, g = girlsb = 3/4g35 students = g + b35 = g + 3/4g35 = 7/4g35/7/4 = g20 girls35 - 20 = b or 3/4(35) = b15 boys
