Answer:
The code is given in images, Button1 and Button2 are for calculating and exit. The sales tax percentage is given. And the form design is also shown in one of the images. Since its textbox, we need to convert the string to double and then back to string to do the calculation, and then post on the textbox again. The this.Close() function closes the form. And textBox1, Show() and for each textbox displays the values in textboxes.
Explanation:
Please check the answer section and images. The button1 and button2 can be changed to Btn_Calc and Btn_Exit if required. For that, we need to rename the buttons with these names, and then click on it to enter the code behind to add the codes. In that case, the button code will be generated with this new name as the method name.
