It is called BODMAS
i.e bracket,of,division,division,multiplication,addition,subtracting
In solving a rational expression, the steps should be followed respectivelly from bracket to subtraction.
an example of a rational expression.
1/2 of 8+6(5+6)-4+7
bracket
6(5+6)=30+36=66
of
1/2 of 8=4
addition
4+66-4+7
70-11
subtraction
70-11=59