Tgerebare many properties of logarithms that are useful for simplifying and solving such as e^ln(x)=x, alog(x)=log(x^a), addition and subtraction rules (log(x)-log(x^2)=log(x/x^2)).
I'm not sure if iit's just me. but angle ABC looks like a right angle (90 degrees). I'm not positive so try to check with someone to see if I'm maybe right.
