Hey there! I'm happy to help!
We know that the perimeter is 2L+2W. Le'ts plug in the values 3 and 5 from our ratio and see what our perimeter would be with that.
2(3)+2(5)
6+10
16
How can we get this 16 to 64?
64/16=4
So, we need to multiply this length and width by four to get 64 as our perimeter!
3*4=12
5*4=20
We can plug this into our perimeter equation
2(12)+2(20)
24+40
64
Therefore, our length is 12 and our width is 20.
Have a wonderful day! :D
