Question

when the length of a rectangle is X inches and the width is y inches, the perimeter is 30 inches. if the length is tripled and the width is quadrupled the perimeter becomes 102 inches. find the length and width of the original rectangle

Answer 1

P1=2x+2y=30

after modify them

P2=2*3x+2*4y=102

6x+8y=102

2x+2y=30 / * (-3)

-6x-6y= -90

6x+8y=102

we must add the 2 expressions

/ 8y-6y=102-90

2y=12

y=12:2

y=6

2*x+2*y=30

2x+2*6=30

2x+12=30

2x=30-12

2x=18

x=18:2

x=9