Here's one that's not so obvious:

Solve  3x = 7

(Harder to guess the answer now, huh?)

Get the x alone...  Who's bugging him?  The 3!

Since the 3 is multiplied with the x, we'll undo him by dividing both sides by 3:

3x / 3 = 7 / 3    So, x = 7/3
 

Hey -- Did you know that you can check these things?

We started with 3x = 7...  and got x = 7/3...   Put it back in!     3x = 7...   3(7/3) = 7 which gives 7 = 7   Yep, it works!


TRY IT:

Solve    5x = 13    *And check it!