The general steps of the mixed operation of addition and subtraction of rational numbers are: (1)________ ;(2)_________ ;(3)________ _______ ;(4)__________________

The general steps of the mixed operation of addition and subtraction of rational numbers are: (1)________ ;(2)_________ ;(3)________ _______ ;(4)__________________

The subtraction into addition to determine whether the symbol can be simple, simple to calculate the results first