14) 2^log2 9 =9
15) 10/10^lg5 =10/5=2
16) 6^(1/log9 6) = 6^log6 9 = 9
17) log5 9 * log9 1/25 = (log9 1/25)/(log9 5) = log5 1/25 = -2
18) log3 12 - ((log7 5)/(log7 3))*log5 4 = log3 12 - log3 5 * log5 4 = log3 12 - (log5 4)/(log5 3) = log3 12 - log3 4 = log3 3 = 1