Let x be the smaller number, y be the larger one.
9 times smaller number is 9*x, or 9x.
We have a first equation: 9x - y = 6
On the other hand, we have: x+y=54 (because their sum is 54).
From those two equations above, we can solve for x and y.
The smaller number is x= 6
The larger number is y= 48.
Hope this helps~