2 log 3 = a dan 3 log 5 = b maka 20 log 15 =?

2log 3= a
3log 5= b

20 log 15 = (log15)/(log20)
(log3 +log5) / (log2^2 +log5)
(2log 3 + 2 log 5) / (2log 2^2 + log5)
=
(a+ ab) / (2+ab)
note:
2log 5= 2log3 + 3log 5

maaf kalau salah y...