The calculation order of the mixed operation of addition and subtraction in parentheses: first calculate the parentheses, then calculate.

External bracket

The order of addition and subtraction without brackets is calculated from left to right.

Add and subtract mixed operations, first look for parentheses. Add-subtract mixed operation with brackets, first in brackets; The calculation order of addition and subtraction mixed operations without brackets is from left to right.

For the general steps of solving problems: first read the meaning of the question, understand the meaning of the question, and then solve the problem with mixed operations. Understanding the meaning of the question is the key and the premise of doing the right thing.