3 * x^(ln 5) = 5 * y^(ln 3)
x^(ln 3) = y^(ln 5)
Raise both sides to the 1/(ln 3) power. You get:
x = y^[(ln 5)/(ln 3)]
Substitute into the first equation
3 * y^[(ln 5)(ln 5)/(ln 3)] = 5 * y^(ln 3)
Divide both sides by 3 and y^(ln 3). You get:
y^[(ln 5)(ln 5)/(ln 3) - ln 3] = 5/3
y^1.26 = 5/3
y = 1.5003 which is approximately 1.5