A.30/(3×0.16×0.20×7.4×0.9) B.30/(3×160×200×7.4×0.9) C.30/(3×160×200×0.9)
A.4 B.7 C.9
A.0.65×(18/12)2 B.0.70×18/12 C.0.70×(18/12)2