If we write the bigger number as x, and the smaller number as y, we can write it as simultaneous equations.
So, if the difference is 5, we can say that
x-y=5
And if five times the smaller number minus the greater number is 7, then we can write that as
5y-x=7
You can add these together to get 4y=12, and if we simplify, we get y=3.
We know that the difference is 5, so 3+5=8.
Therefore, Ethan's numbers are 3 and 8.