The sum of Sally and Beth's age is 60. Six years ago, Sally was 3 times as old as Beth. What are their present ages?

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.