SOLUTION: Thelma wants to find the equation of a line that passes through the point (2,2) and is perpendicular to the line y = 1/2 x +5. Which equation best represent Thelma's equation? A

Those choices all pass through (2,2) so substituing that does no good.

We have to know two things:

1. y = mx+b.  when you see y = ↏x+↏ or y= ↏x-↏ where there are numbers in 
those boxes that the number in the first box is always the slope.

2. If one line has the slope  then a line perpendicular
to it has the slope .  "We flip it and change its sign" 

[That's because : 
a. We flip it because the 'rise' on one line becomes a 'run' on a
line perpendicular to it and vece-versa.
and 
b. We change the sign because if a line goes uphill to the right 
it has a positive slope. A line perpendicular to it goes downhill 
to the right and has a negative slope.] 

So we look at  and see that its slope is ,
So we flip it and change the sign and get  which simplifies
to .  Then we look through the list of choices and find the one
that has a  as a coefficient of x.  Then we see that the only choice
is D.

Edwin