E(Rm)=0.12, Rf=0.05, Betai=0.75
E(Ri)=Rf+[E(Rm)-Rf]*Betai=0.05+[0.12-0.05]*0.75=0.1025
a)NPV=-1000000+(100000/Rm)-(10000/Rf)+50000
=-1000000+(100000/0.12)-(10000/0.05)+50000=-316666.67<0
b)assumption: zero-tax
BetaL=2(levered company)
Ke(cost of equity)=Rf+[E(Rm)-Rf]*BetaL=0.05+[0.12-0.05]*2=0.19
WACC=50%*0.19+50%*0.05=0.12
NPV=-1000000+(100000/WACC)-(10000/Rf)+50000
=-1000000+(100000/0.12)-(10000/0.05)+50000=-316666.67<0
Under the condition of zero tax, the cost of captal does not depend on the capital structure.
So even if the capital structure is changed, the project is still not worthwhile.