Hi Susan,
you could use the Solve[] function to solve these equation:
Solve[(3 r + 6)/9 == (4 r - 24)/4, r]
And if you want to see the step by step solution, you can type in:
==Solve[(3 r + 6)/9 == (4 r - 24)/4, r]
The two equals at the beginning of the line, will start the Wolfram|Alpha mode. So you need an internet connection.
I hope it helps!
