9 less than twice x is twice y

9 less than twice x is twice y

Twice x means we multiply x by 2:
2x

9 less than Twice x means we subtract 9 from 2x
2x - 9

Twice y means we multiply y by 2:
2y

The word is means equal to, so we set 2x - 9 equal to 2y:
2x - 9 = 2y