n
1
2
3
4
…
s
1+3
1+3+5
1+3+5+7
A.34.26 B.42.39 C.37.36 D.28.86
×1.6=
×0=
2÷0.1=
9.8+2=
1.25×0.8=
÷37.5%=
3-=
2.1-140%=
①2.8÷×÷0.7 ②+5.8-+4.2 ③0.4×9×25
2x+2.7=24.7 x-x= =