Jawaban no 3 dan caranya bagaimana?

Bab Logaritma
Matematika SMA Kelas X

2log 3 = a
3log 5 = b

15log 72
= (3log 72)/(3log 15)
= (3log (9 x 8))/(3log (3 x 5))
= (3log 9 + 3log 8) / (3log 3 + 3log 5)
= (3log 3^2 + 3log 2^3) / (1 + b)
= (2 + 3/a) / (b + 1)
= (2a + 3)/(a (b + 1))

jawabannya C