9.72×0.72+0.915×1.2+0.1487×28
=4×(9.72×0.18+0.915×0.3+0.1487×7)
=4×(10×0.18-0.28×0.18+1×0.3-0.085×0.3+0.15×7-0.0013×7)
=4×(1.8-0.0504+0.3-0.0255+1.05-0.0091)
=4×3.065
=12.26