3/4=j-1/2 solve the equation check your solution

3/4= j-1/2
first to add 1/2 to both sides to solve for j 
3/4 + 1/2= j
second you find a common denominator in order to add 3/4 and 1/2, the common denominator would be 4, you would have to change 3/4 at all because the denominator is already 4 but in order to make the denominator of 1/2, 4 you would have to multiply both the denominator and numerator by 2 so 
3/4 + 2/4 = 5/4
so 5/4 =j

to check your answer you plug 5/4 in for j 
3/4 = 5/4 -1/2
again you need to find a common denominator between 5/4 and 1/2 which again would be 4, and again you wouldn't change 5/4 but you would multiply both the numerator and the denominator of 1/2 so 
3/4= 5/4-2/4
5-2= 3 and you would keep the 4 so 
5/4 - 2/4 = 3/4

so j =  5/4