A garden path is made of two rectangular slabs laid end to end in a straight line. One slab measures 10 metres by 3 metres and the other measures 5 metres by 3 metres. What area does the path cover?

Explanation

Laying the slabs end to end makes a strip 15 metres long and 3 metres wide, so the surface covered is 10 times 3 added to 5 times 3. A figure of 36 measures the distance right round that strip rather than the ground inside it, and a boundary length can never be counted in squares.