Question 19111
For {{{y=mx+b}}}form, 
y is your y value
m is your slope
x is your x value
b is your Y-intercept
For {{{y=-x+2}}}
Your slope is -1 and Y-intercept is 2
{{{graph(300,200,-5,5,-5,5,-x+2)}}}
Your second equation, {{{y=(1/2)x-4}}}
Your slope is {{{1/2}}} and Y-intercept is -4
{{{graph(300,200,-5,5,-5,5,(1/2)x-4)}}}
Hope this helps!