Question

The perimeter of a rectangle is 210 m and itss length is 15 m more than double the width. Find its length

Answer 1

Answer:

$let \: the \: lenth \: and \: breadth \: be \: x \\ \: and \: y \: metres \: respectively. \\ perimeter \: of \: rectangle \: = 210 \\ 2(x +y ) = 210 \\ x + y = \frac{210}{2} \\ x + y = 105......(1) \\ according \: to \: the \: second \: condition \\ \: of \: the \: problem : \\ x = 2y + 15.....(2) \\ from \: equations \: (1) \: and \: (2) \\ 2y + 15 + y = 105 \\ 3y + 15 = 105 \\ 3y = 105 - 15 \\ 3y = 90 \\ y = \frac{90}{3} \\ y = 30 \: m. \\ x = 2y + 15 = 2 \times 30 + 15 \\ x = 60 + 15 \\ x = 75 \\ hence \: length \: of \: rectangle = 75 \: m.$