Find the missing number?

Step 1
Take values in the top left and centre circles and put their sum in correspond- ing segments of the lower left circle.

Step 2
Take values in the middle and right hand circles, and put their difference into corresponding segments of the lower right circle.

Missing Number = Lower Right Segment of Middle Circle - Lower Right Segment of the Right Segment.

Missing Number = 7 - 2 = 5.