³log 5=p dan 5^log 4 = q Maka 4^ log 15 =

³log5 = p
⁵log3 = 1/p
⁵log4 = q

⁴log15 = ⁵log15 / ⁵log4
           = ⁵log (5 x 3) / ⁵log4
           = (⁵log5 + ⁵log3) / ⁵log4
           = (1 + 1/p) / q
           = (p + 1) / pq