1. The problem statement, all variables and given/known data Prove: If a < b and c < d then a+c < b+d 2. Relevant equations 3. The attempt at a solution Proof Assume a < b and c < d then a+c < b+c and b+c < b+d so a+c < b+c < b+d therefore a+c < b+d Q.E.D. Pointers and suggestions are also welcome. I am looking for writing and presentation tips just as much as I am for accuracy.