If log(2) = a and log(3) = b are given, then log(5) == log(10) - log(2) = 1 - a we also can consider as given value. THEREFORE, log(150) = log(25*6) = log(5^2) + log(2) + log(3) = 2*log(5) + log(2) + log(3) = 2*(1-a) + a + b = 2 - 2a + a + b = 2 - a + b. ANSWER
----- Multiplying 150 by 2, and then DIVIDING by 2
------- Substituting "b" for log (3), and "a" for log (2)