Hi there!
Let think talk about these clues we have right now...
Luke is x2 more than Lily.
Luce is 45 less candy than Lily since 3 times 15.
225 candys in total...
Let make a random guess...
Lily: 70
Luke: 140
Lucy: 35
Total: 245
Now we know that there must be a half candy since it’s a odd number at the end of that...
Lily: 67.5
Luke: 135
Lucy: 22.5
Total: 225
But we are asked for only Lucy...
So the answer to this problem is 22.5.