Expected Rate of Return for a Portfolio

You are considering two stocks with the following characteristics:

E(R1)=0.10 sigma 0.07

E(R2)=0.20 sigma 0.10

Correlation coefficient=0

Calculate the expected rate of return and the expected risk for the following portfolios:

W1 = 100%

W2 =80%

W3 =50%

W4 =20%

W5 =0%

Please explain how you calculated each.