Double checking my answer

Question

> Double checking my answer <

Find the value of r in (4,r), (r,2) so that the slope of the line containing them is -5/3.

So, the answer is r= -13.

jim_thompson5910 · Answer

I'm getting a different answer. Can you post your work so I can see what went wrong?

anonymous · Answer

Give me about 3 minutes and I can.

jim_thompson5910 · Answer

ok great

anonymous · Answer

Okay, so I got to -5r+20=6-3r
Then I subtracted 20 from 20 and 6 so I got -5r=-26-3r.
I added -5r to -5 and -3.
Then I got -26 = 2r.
I subtracted by 2 from each side and got r = -13.

jim_thompson5910 · Answer

I see where you made the error. 

6 - 20 is NOT equal to -26

6 - 20 is -14

anonymous · Answer

Brain fart.

jim_thompson5910 · Answer

so you should have -5r = -14 - 3r

then you add 3r to both sides to get

-5r = -14 - 3r

-5r + 3r = -14 - 3r + 3r

-2r = -14