The centre of gravity of a trapezium with parallel sides a and b lies at a distance of y from the base b, as shown in the below figure. The value of y is

• A. <img src="/_files/images/mechanical-engineering/engineering-mechanics/29-73-2.png">
• B. <img src="/_files/images/mechanical-engineering/engineering-mechanics/29-73-3.png">
• C. <img src="/_files/images/mechanical-engineering/engineering-mechanics/29-73-4.png">
• D. <img src="/_files/images/mechanical-engineering/engineering-mechanics/29-73-5.png">