The sum of any integer and its opposite is equal to zero. Summary: Adding two positive integers always yields a positive sum; adding two negative integers always yields a negative sum. To find the sum of a positive and a negative integer, take the absolute value of each integer and then subtract these values.
Adding two even numbers will always result in an even number. Adding two odd numbers will always result in an even number. Adding one even and one odd number will always result in an odd number.
Your intention with the wording "consecutive integers of 12 feet" is not clear. Shown are triangles with sides 12 and 13 (a nice Pythagorean triple) as well as 11 and 12.
