Answer:
gcd(20a,14b)
Explanation:
add 7a and 3a, and add 5b to 2b,
you're left with 10a + 7b, times two to both, and you have
20a + 14b
so the answer is gcd(20a,14b)
i have no clue i haven't done this before so thats what i'm guessing happens? good luck :,)