Here is a right-angled triangle (base = 8cm and height = 9cm) and a rectangle (length = 16cm). The area of the rectangle is 6 times the area of the triangle. Work out the width of the rectangle.
Area of triangle is 0.5 x base x height.
0.5 x 8 x 9 = 36
Area of rectangle is 6 x 36 = 216
Area of rectangle is also 16 x width
16 x width = 216
(Divide both sides by 16)
width = 216/16 = 13.5
HW