Problem description:

Football consists of regular pentagonal leather blocks (black) and regular hexagonal leather blocks (white). Use the number x of regular hexagonal blocks to represent the number y of regular pentagonal blocks, and point out variables and constants. (Hint: Each white leather block is surrounded by three black leather blocks. )

Analysis:

Every black one is connected with five white ones, so if there are Y black ones, there should be 5Y white ones.

And each white one is connected with three black ones, so the white one is only: 5Y/3.

So: X=5Y/3

Y=3X/5

X, y variables

3/5- constant