Question

The length of a rectangle is 12 cm less than five times its breadth. The length is 78 cm.​

Answer 1

Answer:

Step-by-step explanation:

Let width = x

length = 5x-12

Perimeter = w+w+l+l or Perimeter = 2w+2l

156=x+x+5x-12+5x-12  Combine like terms

156=12x-24 Add 24 to both sides

156+24=12x-24+24  simplify

180=12x  Divide both sides by 12

180/12=12x/12

x=15  

Next calculate the length

length = 5x-12 = 5(15)-12

length = 63

Dimensions are 15 cm x 63 cm

Answer 2

Let width = x

length = 5x-12

Perimeter = w+w+l+l or Perimeter = 2w+2l

156=x+x+5x-12+5x-12 Combine like terms

156=12x-24 Add 24 to both sides

156+24=12x-24+24 simplify

180=12x Divide both sides by 12

180/12=12x/12

x=15

Next calculate the length

length = 5x-12 = 5(15)-12

length = 63

Dimensions are 15 cm x 63 cm