Answer
r=7
Work Step by Step
13-3r+2+6r-2r-1=3+2$\times$9
First combine like terms
(13+2-1)+(-3r+6r-2r)=3+2$\times$9
14+r=3+2$\times$9
Then multiply
14+r=3+18
Then subtract 14 from both sides
r=3+18-14
r=21-14
r=7
Check the answer.
13-3(7)+2+6(7)-2(7)-1=3+2$\times$9
13-21+2+42-14-1=3+18
(-8)+2+42-14-1=21
(-6)+42-14-1=21
(36)-14-1=21
(22)-1=21
21=21
