Question 238416
For this problem: 
{{{(3/4)x+30=84}}}

You want to get x by itself, first subtract 30 from both sides of the equation:

{{{(3/4)x=84-30}}}
{{{(3/4)x=54}}}

Next, to get x by itself you would multiply the reciprocal of 3/4 to both sides of the equation:

{{{(4/3)(3/4)x=54(4/3)}}}

Now, your left with x by itself, but combine the other like terms:
{{{(54/1)(4/3)=216/3}}}
{{{x=216/3}}}
{{{x=72}}}