How do I solve this problem using logarithm?

75*10^2x =300

Iwant to know what 3g+5h+4g-2h is my teacher is too selfish to tell us

The lengths of all sides of a triangle are integers when measured in decimeters. one of the sides has length of 1 dm and another of 3 dm. find the perimeter of the triangle.'

*segment an is an altitude of right ? abc with a right angle at a. if ab = 2root 5 in and nc = 1 in, find bn, an, ac.