Please solve the problem

step by step why its going to be increase or decrease?

Cast Construction's stock is currently selling at $30 per share. The firm is a mature firm and it has been experiencing a 6% annual growth rate. The risk free rate is 8% and the market portfolio risk premium is 5%. If systematic risk increases by 50%, buy how much the share price will increase or decrease? A. increase by $7.31 B. increase by $4.05 C. decrease by $7.31 D. decrease by $4.05