Question

the perimeter of rectangles is 40 m the length of rectangles is 4cm less than 5 times it's breadth find the length of rectangles

Answer 1

$let \: breadth \: be \: x \\ length =5x - 4 \\ perimeter \: of \: rectangle = 40 \\ 2(l + b) = 40 \\ 2(5x - 4 + x) = 40 \\ 2(6x - 4) = 40 \\ 6x - 4 = 20 \\ 6x = 20 + 4 \\ 6x = 24 \\ x = \frac{24}{6} \\ x = 4 \\ length = 5x - 4 \\ = 5(4) - 4 \\ = 20 - 4 \\ = 16cm$