So first step is to get the 2r all alone.
-7.8 = 4.4 +2r
to do this you must subtract 4.4 from both sides. This will cancel it on the right side and add it to the left side
-7.8 = 4.4 + 2r
-4.4 = -4.4
Now, you are left with the "2r all alone" from here you have to divide by 2 to get rid of it on the right side. Whatever you do to one side you must do to the other. So you are dividing both sides by 2.
-12.2 = 2r
-6.1 = r
^that is your solution.
So first step is to get the 2r all alone.
-7.8 = 4.4 +2r
to do this you must subtract 4.4 from both sides. This will cancel it on the right side and add it to the left side
-7.8 = 4.4 + 2r
-4.4 = -4.4
Now, you are left with the "2r all alone" from here you have to divide by 2 to get rid of it on the right side. Whatever you do to one side you must do to the other. So you are dividing both sides by 2.
-12.2 = 2r
-6.1 = r
^that is your solution.
