Bugfixed.
This application lets you to calculate the unknown term of any kind of proportion including continuous proportions.
To calculate a proportion check one of the four checkboxes to select the unknown term, enter the desired values in the remaining fields and press "Calculate" button.
To calculate continuous proportions you must check two checkboxes (the A and D checkboxes to calculate the extreme terms or the B and C checkboxes to calculate the central terms), enter the desired values in the remaining fields and press "Calculate" button.
To restore the application to the initial values just press "Reset" button.
The application also allows you to view the steps that lead to the solution.