168+42= 0.27÷0.9= 1.25×3.7×0.8= 0.75×0.75=
1- + = 18÷ = ( + )×12= + × =
①360÷15-2.5×1.4
②( + )×23+
③6.875- + -
④ ÷ + ×
⑤4÷ - ÷4
⑥ ×[ ÷( + )]