2.5×20.5+7.5×20.5=(+)×20.5
(1.7×2.5)×=1.7×(×4 )
7.4×0.987.4 2.6×4.54.5×2.6 3.6÷0.33.6
0.07×0.8= 1.7×0.03= 0.16×0.5= 4.5×0.03=
0.63÷0.9= 10×0.74= 0÷3.68= 0.48÷0.03=
1.25×0.8= 0.25×4.3×4=
14和35