Question 1190294
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First you need to subtract 15x from both sides to undo the addition
{{{15x + 18y >= 125}}}


{{{15x + 18y -15x>= 125-15x}}}


{{{18y >= -15x+125}}}


Then divide both sides by 18 to undo the multiplication on y
{{{18y >= -15x+125}}}


{{{18y/18 >= (-15x+125)/18}}}


{{{y >= (-15x)/18+125/18}}}


{{{y >= (-15/18)x+125/18}}}


{{{y >= (-5/6)x+125/18}}}
The entire time, the inequality sign stays the same. It only would flip if you multiplied or divided both sides by a negative number (which in this case didn't happen)


The inequality is now in slope intercept form
It's of the form {{{y >= mx+b}}} 
The boundary is {{{y = mx+b}}}


m = -5/6 is the slope
b = 125/18 is the y intercept


To graph this, you'll graph the boundary line {{{y = (-5/6)x+125/18}}}. It's a solid boundary line and you'll shade above the boundary. 
The solid boundary is due to the "or equal to" as part of the inequality sign.
Points on the boundary are part of the shaded solution set region.
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