If I understand your question correctly you are asking if decimal answers occur because of the "operation" type. It is true that division can produce a decimal answer if the problem is set up that way, with a decimal point, otherwise division will produce a "remainder" usually expressed as a whole...

A trapezoid is a quadrilateral. All quadrilaterals have four angles whose sum is 360 degrees. If two of the angles are right angles, that accounts for 180 degrees of the total. Therefore, the other two angles must total 180 degrees as well. Any combination of angles/degrees that equals 180 would work...