Ok so first you have to open the parenthesis. Since the sign to the left of both the parenthesis is positive we can just normally open the parenthesis .
We get: 1/2a+12+4/5a+7
We need to convert the denominators of 1/2a and 4/5a so we can add them together
1/2a=5/10a
4/5a=8/10a
Now we can add the a variables together.
5/10a+12+8/10a+7=
13/10a+12+7
Then add 12 and 7 together:
13/10a+19 = 1 3/10a+19
Keep in mind: If the sign to the left of the leftmost parenthesis is negative then the sign inside the parenthesis is negative.
For example when opening this parenthesis: (2+3/x<u>)-(2+3x)</u> the sign is negative so the opening parenthesis is -2-3x.
