What is the best way to solve letter f?

Turn the exponents and radicals into fractional exponents
So it would be
Log (base) b of (X^1/4 x Y^3/2)
Hope this was helpful

38+105= 143, 39+104=143, and you will find then adding the numbers on opposite sides, moving inwards yields the answer 138 every time. because of this, you’re going to multiply 138 times the number of pairs, which is 34. therefore, 34*138= 4692(i’m sorry if it’s the wrong numbers, but it’s the right concept)