A triangle and a parallelogram are constructed on the same base such that their areas are equal. If the base and the altitude of the rectangle are 20 cm and 25 cm respectively then, what will be the value of the altitude of the triangle?

Area topics are: Area of rectangles, squares, triangles, quadrilaterals, polygons, and circles.

Here are some area formulas for quantitative aptitude:
Rectangle: Area = (length x breadth)
Square: Area = (side)2 = (diagonal)2
Triangle: Area = x base x height
Parallelogram: Area = (base x height)
Circle: Area = R2, where R is the radius
Trapezoid: Area = 1⁄2 × (base + base) × height
Room walls: Area = 2 (length + breadth) x height
Circumference of a semi-circle: Circumference = R