1.32.5/2.5=13 1.36*0.05=0.068 0.06*1.7=0.102 2.08*75=156 49/2.18.85 3.2/0.46=5
2.31.8*1.2=1.2*31.8
(2.5+3.5)*4=2.5*4+3.5*4
(1.5*1.2)*6=1.2*(1.5*6)
3.(1)2.1*1.5=3.15 (2)1.8*1.8=3.24 (3)2*1.43=2.86
4.2033.9/12~169.49mm
5.(52-4)*4=12