Answer:
the company's cost of equity capital is 14.75 %.
Step-by-step explanation:
WACC = ke × (E/V) + kd × (D/V)
Where,
ke = cost of equity
 = this is unknown
E/V = Weight of Equity
 = 55%
kd = cost of debt
 = Interest × ( 1 - tax rate)
 = 12% × ( 1 - 0.40) 
 = 7.20 %
D/V = Weight of Debt
 = 45%
Therefore, 
WACC = ke × (E/V) + kd × (D/V)
11.35% = 55%ke + 7.20 % × 45%
11.35% = 55%ke + 3.24 %
55%ke = 8.11 %
ke = 14.75 %