12和36 16和40 30和45
+ = - = 3- = + - + =
2÷3= +0.6= 0.32= 1- + =
① ② ③
④-(-) ⑤-+- ⑥3.75-+-
① - +
②1+1.9+2.9+3.9+4.9+5.9
③ - + -
④ -( + )-
⑤5- +
⑥2.8×0.5+5×2.72