To ensure that a combo box will appear within a rectangle, change the property to transparent.

To ensure that a combo box will appear within a rectangle, change the back style property to transparent. 
A combo box is normally a type of a dialogue box containing a combination of controls, such as sliders, texts boxes and some drop-down lists. Black style property is used to specify whether a control will be transparent. 

The answer is 15×7=105therefore, 105×5=525 miles