7.8÷0.2=
×2-3.5=
12×(-)=
-+=
4×(1-10%)=
-62.5%=
+50%=
÷+×2=
×(+)÷ 37×60%+×37+37 ÷[(+)×]
×(25×32)×
3.06-[1.8×(2.41-1.91)]
50%×2.5××64 32 × (+)
(1-75%)÷(1+) ÷[( -0.75)×60%]