Let x be the number of red beads.

1/4 of 20 is x

1/4 * 20 = x

x = 5

¼ of 20 = ......

20 beads in total.

1/4 of them are Red.

So ..

5 are Red .. 20/4 = 5

and 15 are Green .. 20 - 5 = 15