One number must be negative since the product of the 2 number is negative (5 x -8 = -40). They both cannot be negative, if they were the product would then be positive. The negative number must have a absolute value that is larger than the positive, the negative numbers distance from 0 must be larger than the positive, -8 has a distance of 8 and 5 has a distance of 5. The sum of the two numbers is