PLEASE SHOW ALL WORK - I HAVE A FINAL ON THIS TOMORROW :( AND DONT UNDERSTAND

a. You own a stock portfolio invested 35% in stock Q, 25% in stock R, 30% in stock S, and 10% in stock T. The betas for these four stocks are 0.84, 1.17, 1.11, and 1.36, respectively. What is the portfolio beta? b. You own a portfolio equally invested in a risk-free asset and two stocks. If one of the stocks has a beta of 1.27 and the total portfolio is equally as risky as the market, what must the beta be for the other stock in your portfolio?