Please show excel formulas so I can learn how to do this on my own. Thank you..

Portfolio Beta

Your retirement fund consists of a $7,500 investment in each of 20 different common stocks. The portfolio's beta is 1.45. Suppose you sell one of the stocks with a beta of 1.0 for $7,500 and use the proceeds to buy another stock whose beta is 1.25. Calculate your portfolio's new beta. Do not round intermediate calculations. Round your answer to two decimal places.

Portholo Bets