The triangle that does not have the y angle, equate all of its angles to 180 degrees and solve for x. Once you solve for x, substitute that value to the angles in the other triangle, and then add them all up and equate it to 180 degrees to solve for y.
I assume you meant to write 5^c = 125. The equivalent logarithmic expression for this would be ㏒₅125=c.
