6 years ago, the sum of their ages would be 12 less than it is now.
60 - 12 = 48.
Now, if one was three times as old as the other, then we need to find 4 equal parts. 48 divided by 4 is 12. So, 6 years ago, Beth was 12 and Sally was 36.
So, now we put the 6 years back on to each, and get:
Sally is 42 and Beth is 18.
That is the easiest way i can see, but there might be a better way to do it.
