Does anyone know how to do this

m+n=140

Step-by-step explanation:

While it may seem you need to find the measure of m and n, you don't. Looking at the angle with measure of 40 degrees you can see inside the triangle that the top angle is congruent to the angle of 40 degrees. Now that you know that the top of the angle is 40 degrees then knowing a triangle is 180 degrees total you can infer that m+n=140 because adding 140 to 40 is also 180.

you didn't post any answer choices, so its not 100% clear what your teacher is looking for

however, log(15/7) is equivalent to log(15) - log(7)

i'm using the rule log(x/y) = log(x) - log(y)