My seven year old was set this question and I was asked to solve. Help please.

Question

Here is the question:
My number has 5 tens. The ones digit is less than the tens. What could the number be?

My solution was 5 x 10 = 50. Then subtract 1 from the tens = 49 is this correct?

Answer 1

5 tens = 50

ones digit is less than the tens

54, 53, 52, 51, 50