Answer:
(1) If the GCD of 5 and 12 is 1, then they are co-prime.
(2) The sum of 5 and 12 is 7 if and only if 5 is a negative integer.
Step-by-step explanation:
(1)
The GCD (greatest common divisor) of two or more numbers, which are not all equal to zero, is the largest positive integer number which divides each of the numbers.
If the GCD of two numbers is 1, then the two numbers are known as coprime or relatively prime or mutually prime.
(2)
The sum of 5 and 12 is 7 if and only if, the number 5 is a negative integer, i.e.
-5 + 12 = 7