Question 431945
Here's the graph:
{{{ graph( 400, 400, -6, 6, -6, 6, x + 4, -3x) }}}
I notice that {{{ y = -3x }}} goes through the origin,
because when {{{x=0}}}, {{{y=0}}}. 
And, {{{y = x + 4}}} intersects the y-axis at {{{y=4}}}
since {{{ y = 0 + 4 }}}.
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Using substitution, 
{{{y = x + 4}}}
{{{-3x = x + 4}}}
{{{-4x = 4}}}
{{{ x = -1}}}
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and
{{{y = x + 4}}}
{{{y = -1 + 4}}}
{{{y = 3}}}
The lines meet at (-1,3)
The area is {{{(1/2)*b*h}}}
{{{b}}} would be the side on the y-axis, {{{4}}}
The height would be the shortest distance 
from (-1,3) to the y-axis, which is {{{1}}}
(don't use (-) signs when finding distance)
So the area is {{{(1/2)*4*1 = 2}}}