The length of a rectangle is twice its width. The perimeter of the rectangle is 90 cm. What are the length and width?

Question

I cannot figure out this answer at all I have tried doing it ten times can u please help me 

Answer 1

width = w

length =2w

 

perimeter =2(length + width)

90  = 2(2w+w)

90 =2(3w)

90=6w

15 =w

 

width = w=15cm
length =2w=30cm