What is the expected risk- free rate of return if asset X, with a beta of 1.5, has an expected return of 20 percent, and the expected market return is 15 percent? Can please explain step by step how to solve this problem.

I dont know how to solve it after this?

Expected return of Stock = risk- free rate of return + Beta*( expected market return - risk- free rate of return)

20% = risk- free rate of return + 1.5* (15% - risk- free rate of return)