Rectangle and triangle...A rectangle and a triangle have the same area. When placed on the same level, the tip of the triangle touches the top edge...

By the given discrpition  the triangle has the same
altitude from its base as a distance between the two parallel sides of the
rectangle.

Let this altitude of the triangle be
h.

Area of the rectangle = 150 sq cm,
given.

Therefore the base of the rectangle =
150/h.

Since the  triangle has the same area as that of the
rectangle, the base 150 sq cm = (1/2) *base*height.

150 =
(1/2) base of triangle *h.

base of the triangle = 2*150/h
=  2(base of rectangle).

Therefore the base of the triangle
is twice the base of rectangle.