(1- )5 - + -
3.8×99+3.8 2.8+4.36+5.64 [×(-)]÷
×75%+× 50%+0.5+ 5×7×()
7.8÷0.2=
×2-3.5=
12×(-)=
-+=
4×(1-10%)=
-62.5%=
+50%=
÷+×2=