Notice that 0.2 = 1/5. Therefore, log(0.2) == log(1) - log(5) = 0 - 0.6990 = -0.6990. Now, we are given = 0.2. Take logarithm base 10 of both sides. You will get 2x = log(0.2) = as we deduced above = -0.699. Hence, x = -0.6990/2 = -0.3495. ANSWER CHECK. = 0.2000 (rounded), which confirms the solution.