the question in attachment an aeroplane on airport runwa

the question in attachment
an aeroplane on airport runway. When its engine is running the vertical reaction that the ground exerts at point A is measured by means of a scale as 5 kN. When the engine is turned off however the vertical reactions at points A and B are 3.75 kN each.
The difference in readings at point A is caused by a couple acting on the propeller when the engine is running. This couple tends to overturn the plane counterclockwise which is opposite to the clockwise rotation of the propeller.
Determine the magnitude of this couple and the magnitude of the vertical force exerted at point B when the engine is running
(20 mark )
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