70 = 7 * 2 * 5
Since the greatest common factor is 7, and 7 is a prime, 7 must be the only common factor besides 1.
Thus, one of the number must have the factor 2 and the other number must have the factor 5, since 70 is the lowest common multiple of the two numbers.
Hence, one number is 7 * 2 = 14, and the other number is 7 * 5 = 35