Fractions! This is pretty cool!

Sum-Part-Part-Product
This one is kind of hard to explain, but I'll try. Basically, you are given 2 of the above and are expected to find the other 2 that are missing. Ex: you may be given the sum and the product and you will need to find the 2 numbers/fractions that both add up to the given sum and multiply together to get the given product.

http://www.themathlab.com/gym/brainbuilders/table/sumpppr/sum_prod.htm