so the equation is 3/4x + 1/2x since the denominator (the number on the bottom) is not the same we are going to have to change it. since one of them is a 4 then we can change the other one to a 4 as well. 1/2 x 2/2 = 2/4. Now all of the the numbers on the bottom are the same we can know just add. 3/4x + 2/4x = 5/4 x.
5/4 x is the improper fraction. The mixed-number fraction is 1 1/4.
Hope this helps.