1. Move the orange points to change the values of \(a\), \(b\), \(c\) and \(d\).
  2. Move the point marked in the following picture to select the intended operation (addition, subtraction, multiplication or division).
  3. Observe the diagram for different values of \(a\), \(b\), \(c\) and \(d\).
  4. The applet displays a tip that helps find the value of the operatation. To see it turn black button "on".

    The tip shows the value of the operation in a scheme at the right side of the applet.
  5. Find out the value of the operation.
  6. To check your solution, turn green button "on".