Help on 7 grade math!!!

here is the question...
Rectangular cake pans X and Y are similar. The Ratio of the width of pan X to the width of pan Y is 3 : 4. The length of pan X is 10 inches, and its width is 5 inches. What is the perimeter of pan Y?

x:y = 3:4
P of x= 10+10+5+5= 30
x:y= 3:4= 30:y
3:4= 30:y
y= 40

pan Y length=10*4/3
pan Y width=5*4/3
perimeter=2(40+20)/3=40 inches