Question 116417
You need to get your equation into the slope-intercept form of a line.
{{{y=mx+b}}}
{{{3x+4y=16}}}
{{{4y=16-3x}}}
{{{y=4-(3/4)x}}}
{{{y=-(3/4)x+4}}}
The coefficient in front of x, m, is the slope of the line.
{{{m=-(3/4) }}}
The number b is the y-intercept, the value at x=0; y=4. 
{{{ graph( 300, 300, -10, 10, -10, 10, -(3/4)x+4) }}}