31.9-3.09=
×÷×=
1.7×101=
+=
50%+30%=
3.14÷0.5÷2=
:=
(+)×24=
0.125×0.25×32 0.375×3.4+4.6×
(-+)÷ 6.72-2.3÷0.5×0.8