[tex]-3(1+6r)=14-r\\-3-18r=14-r\\-3-17r=14\\-17r=17\\r=-1[/tex]
Steps: Distribute -3
Add "1r" to both sides
Add 3 to both sides
Divide both sides by -17
-3(1 + 6r) = 14 - r Distribute/multiply -3 into (1 + 6r)
(1(-3) + 6r(-3)) = 14 - r
-3 - 18r = 14 - r Add 18r on both sides
-3 - 18r + 18r = 14 - r + 18r
-3 = 14 + 17r Subtract 14 on both sides
-3 - 14 = 14 - 14 + 17r
-17 = 17r Divide 17 on both sides
-1 = r
[proof]
-3(1 + 6r) = 14 - r Plug in -1 into "r"
-3(1 + 6(-1)) = 14 - (-1)
-3(1 - 6) = 14 + 1
-3(-5) = 15
15 = 15
