Isolate the variable "r". Add 2r to both sides, while subtracting 16 from both sides. You will be left with -20=5r. Then you need to divide 5 from both sides. Your answer will be -4=r.
[tex]-2r-4=3r+16\ \ \ |+4\\\\-2r=3r+20\ \ \ |-3r\\\\-5r=20\ \ \ \ |:(-5)\\\\r=-4[/tex]
Answer: r = -4
