Question 984510
The first thing you need to know is that the slopes of perpendicular lines are negative reciprocals. Let's find the slope of the given line
{{{3y= 7x - 4 }}}
{{{y = (7/3)x - 4/3}}}. 
The above equation is in the slope intercept form, so its slope is {{{7/3}}}

The negative reciprocal is {{{-3/7}}}. 
That is the slope of the line you are asked to find. So our equation is in the form
{{{y = (-3/7)x  + B}}}  where B is the intercept

You are told the line includes point (7,2).
Plug in that point and solve for B
{{{2 = (-3*7)/7 + B }}}
{{{2 = -3 + B}}}
{{{5 = B}}}

Plug that in and get {{{y = -3x/7 + 5}}}