Question 9546
what you need to do is to first isolate "y" on one side:
y-{{{3/4}}}={{{5/6}}}      <--add {{{3/4}}} to both sides to isolate the variable "y"
y-{{{3/4}}}+{{{3/4}}}={{{5/6}}}+{{{3/4}}}
y={{{5/6}}}+{{{3/4}}}


the denominators are not the same.  You need to find the least common multiple for both 6 and 4 is 12.  
What do you do to 6 to get to 12?  multiply by 2
what do you do to 4 to get to 12?  multiply by 3

y={{{5/6}}}{{{(2/2)}}}+{{{3/4}}}{{{(3/3)}}}
y={{{10/12}}}+{{{9/12}}}
y={{{19/12}}}
y=1 {{{7/12}}}