Question 21314
7/y - 1/3  = 1/4
First you need to add {{{1/3}}} to each side;
{{{7/y}}}-{{{1/3}}}+{{{1/3}}}={{{1/4}}}+{{{1/3}}}
Find common denominators of {{{1/4,1/3}}} so you can add;
{{{7/y}}}={{{4/12}}}+{{{3/12}}}
{{{7/y}}}={{{7/12}}}
Now multiply each side by y;
(y){{{7/y}}}={{{7/12}}}(y)
7={{{7/12}}}y
Multiply each side by the reciporcal of {{{7/12}}}, which is {{{12/7}}};
{{{(12/7)}}}7={{{7/12}}}y{{{(12/7)}}}
The 7's cancel each other out on the right side, and on the left {{{7/12}}}*{{{12/7}}}cancel's out;
12=y
Hope you understand
=)