The one in the title is different than the picture so I'm going to solve the picture and hope that is what you are looking for.
First we must find the least common multiple of 2 and 4. It is 4.
To get the denominator of the first term, 1/2, to be 4 we must mulitply both top and bottom by 2.
(1/2)(2/2) = 2/4
The number 2 is the same as the fraction 2/1. To get it to have the denominator of 4, we multiply both top and bottom by 4
(2/1)(4/4) = 8/4
Now we solve.
2/4 - 3/4 + 1/4 + 8/4
2/4 + 1/4 - 3/4 + 8/4
3/4 - 3/4 + 8/4
0 + 8/4
8/4 = 2
The answer is 2
OR
(2 - 3 + 1 + 8) / 4
(- 1 + 1 + 8) / 4
(0 + 8) / 4
8 / 4
2
The answer is 2