Question

How do you do addition and subtraction with a negative number and a positive number?

Answer 1

addition - eg. -1 + 2 = 2 
so, instead of adding u will subtract the number. 
Subtraction - eg. 4 - (-3) =7 
So, instead of subtracting you will add the number. 

Answer 2

In positive numbers we do like this
 22                                       17
+11                                     -14 
 33                                        03

In negative numbers we do like this
-6 - (-7)                                    -6 + (-7)
= +1                                      = -13