So since these are similar all you need to do is creat a ratio for each rectangle.
X/20 is the first rectangle and 6/14 is second. Whichever edge you put on top for the first, you also need to for the second.
Now set them equal to each other and cross multiply.
X 6
__ = __
20 14
14x= 120
Now divide by 14 on both sides
14x= 120
__ ___
14 14
X=14/120
Now finally simplify. I’m dividing by two since it goes into both.
7/60 would then be your answer