Answer
log (50 * 200) = 4
Work Step by Step
1.The Law that will be used here is $log_{a}$ (AB) = $log_{a}$ (A) + $log_{a}$ (B).
2. Combine 50 and 200 to get $log_{10}$ (50*200) = $log_{10}$ (10000).
3. Evaluating $log_{10}$ (10000) gives you the answer of 4.
4. If evaluating the log way is harder, convert $log_{10}$ (10000) to $10^{x}$ = 1000, Solving for X, the exponent, will also give you 4.