Answer:
r=

Explanation:
You would want to isolate the r by itself by doing all the opposite operations.
First, you can divide the L to get
1-r =

Next, move the 1 to the other side to get
-r=

Then, we would not want to keep the negative so, move it to the other side to get
r=

(Note the 1 changed to a positive because we move the negative to the other side so, negative or negative 1 will be positive.