Question

The length of a rectangular piece of land is 9 cm more than 3 times its width. The perimeter is 418 cm. Find its dimensions.

Answer 1

Let w represent the width of the rectangle in cm. Then its length in cm is (3w+9). The perimeter is the sum of two lengths and two widths, so is ...

... 418 = 2(w + (3w+9))

... 209 = 4w +9 . . . . . . divide by 2, collect terms

... 200 = 4w . . . . . . . . subtract 9

... 50 = w . . . . . . . . . . divide by 4

... length = 3w+9 = 3·50 +9 = 159

The dimensions of this piece of land are 159 cm by 50 cm.