Hey! I know this is a bit late, but I realized I had the same question! Here is the answer to the question ;3Hope I helped! :D
Coin 1:The top box on the coin 1 section is QThe bottom box on the coin 1 section isNCoin 2:The first box on coin 2 is NThe second box is QThe third is QThe final box is N !Good luck~!
The answer is 5.
you can turn it into a fraction ratio (6 over 15 is equal to 2 over c) and then cross multiply
F(X) = (3x + 5)/X
F(a + 2) = (3(a + 2) + 5)/(a + 2)
F(a + 2) = (3a + 6 + 5)/(a+2)
F(a + 2) = (3a + 11)/(a + 2).
This would be the final solution.