Joseph has 1170 $1 coins.

He has 225 less 50-cent coins than $1 coins.

The number of 20-cent coins is 315 more than the number of $1 coins.

What is the ratio of the number of 20-cent coins to the number of 50-cent coins to the number of $1 coins?

Notes to students:

1. If your answer is a ratio, leave it as a:b