Quandaries and Queries I am parent who it trying to help her daughter.WE just cannot figure out how to do these sum and difference problems. This is the problem. Find two numbers that have a difference of 13 AND A SUM OF 75? We need to learn about the formula or procedure. Thanks Vicki 6th grade Hi Vicki, I would use my number sense and some checking to solve this problem. You want the sum of two numbers to be 75. If you took both numbers to be half of 75 then their sum would be 75 and their difference would be 0. Half of 75 is 37 1/2 which is not an integer so try 37 and 38. These two numbers, 37 and 38 have a sum of 75 and d difference of 1. I want a larger difference but maintain the sum as 75. If you add 1 to 38 and subtract 1 from 37 you maintain the sum as 75 (you added 1 and subtracted 1) but now the difference is 3. If you add 2 to 38 and subtract 2 from 37 you maintain the sum as 75 (you added 2 and subtracted 2) but now the difference is 5. Now I can see what to do. With 37 and 38 you have a difference of 1 and you want to increase the difference to 13. If you add 6 to 38 and subtract 6 from 37 you should have a difference of 13 and a sum of 75. Check to see if this works. Penny