if fn=29, what is the value of r?

So what you would do is: you know that the whole segment equals 29. If you add 4r-3+ r+7= 29. You need to isolate the variable, in this case,r. So you start by combining like terms on one side so you would get 5r + 4=29. Then subtract 4 from both sides. You would then get 5r=25. Divide both sides by 5, and you get r =5