You hold three stocks in your portfolio: A, B, and C. The portfolio beta is 1.40. Stock A comprises 15% of the dollar value of your holdings and has a beta of 1.0. If you sell all of your investment in A and invest the proceeds in the risk-free asset, your new portfolio beta will be:

A) 0.60

B) 0.88

C) 1.00

D) 1.25

E) 1.40

Answer is D. My question is: how to get D answer. Please show step-by-step calculation clearly. Thanks