Please solve it in excel step by step

Suppose that the market models for stocks A and B are estimated from realized returns with the following results TA= 0.02 +0.9rn + EA TB = -0.03 +1.27m +EB where standard deviation of market return is om = 25%, RA = 0.5, and Rg = 0.8 a. [2pts) Which stock has more systematic risk? b. [2pts] Which stock has more total risk? c. [2pts) Which stock has more firm-specific risk