maths
posted by david .
A large canal will have a crosssection in the shape of an isosceles trapezoid. The top will be twice as wide as the bottom, and the depth will be 8.00 m. Because of the cost of the building materials, the bottom and two slopes sides are to measure 14.0 m altogether. What is the area of the crosssection?

If the sloping sides measure x each, then the bottom is 142x.
So, the crosssection has area 1/2 (8) (142x + 2(142x))/2 = 12(7x)