This applet allows you to play around and so learn how to solve simple equations. Solving equations means finding the value of the variable x.
Every time you click "New Problem" a new equation appears for you to solve. There are five levels of difficulty which you can choose from the drop-down menu at the top. You'll see 4 sliders at the bottom of the page, and each one allows you to make changes to the equation.
1 - Add or take away x's  
2 - Add or take away numbers.
3 - Multiply by a number.  
4 - Divide by a number.

To solve the equation you have to do the correct things in the correct order, and this applet allows you to practise that, and so understand the process.
As you drag a slider left and right, you'll see some writing appear on the screen. This tells you what will happen when you release the slider. In other words, you must decide what you want to do, drag the slider to the correct position, and then release it. You will then see the equation change.
The end will come when you have found the value of x, and you see "x = ....." and a message. Play around. Don't worry if at first you make a mistake. You can always press "Start again". Good luck!