A man is 3 times as old as his daughter, 8 years ago the product of their ages is 112, find their present ages

Notice: 
Factors of 112 are 
1, 112 
2, 56 
4, 28 <--- most likely ages 8 years ago!
7, 16 
8, 14 



Now we verify... 
3(4+8)=36=28+8 

so their ages are 12 and 36