Draw a polygon with area equal to 7.5 square units.
Draw a triangle with a height of 3 and a base of 5. Since the area of a triangle is equal to (bh)/2 the area would be (3*5)/2 = 7.5 sq units
Draw a triangle with a height of 3 and a base of 5. Since the area of a triangle is equal to (bh)/2 the area would be (3*5)/2 = 7.5 sq units