please explain why the answer become the following

The market portfolio has an expected return of 18% and the risk-free rate is 6%.An nvestor borrows $100 at the risk-free rate and invests this and a further $100 of his own n the market portfolio. What is his expected return? Portfolio=(2market)+(1loan)=(21)+0=2 Expected return =6%+2(18%6)=30%