() () ()=1
() ()= ()
() ()
+ + +
- + +
+ = + = - = - =
- = - = + = - =
- = 1- = + = + =
+ = + = ﹣ = 1﹣ =
+ = 700×4= 62﹣36= 700+300=
123×2= 486+14=
7.2-3.9= 5.8-4.5= 0.89+0.21= 15.2+14.8=
= = = =
= = = =
80×2= 24×2= 350-70= 500×4=
28×0= 83-9= 45÷5= 230×2=
+ = - = + = 1- =
1- = - = + = +2=
1- - =