=7.2x14.5+(14.5+2+0.7)x2.8=14.5x(7.2+2.8)十2x2.8+0.7x2.8=14.5x10+5.6+1.96=152.56
7.2x14.5+17x2.8 =7.2x14.5+(14.5+2.5)x2.8 =(7.2+2.8)x14.5+2.5x2.8 =145+7 =152
