The task is to generate the correct answer for a given math problem.

Q: Problem: a train passes a station platform in 36 sec and a man standing on the platform in 25 sec . if the speed of the train is 54 km / hr . what is the length of the platform ?

A: 165 
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Q: Problem: if 4 xz + yw = 10 and xw + yz = 20 , what is the value of the expression ( 2 x + y ) ( 2 z + w ) ?

A: 50 .
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Q: Problem: in the figure given below , abc and cde are two identical semi - circles of radius 2 units . b and d are the mid points of the arc abc and cde respectively . what is the area of the shaded region ?

A:
2 π - 4', 'd ) ½ ( 3 π - 1 )', 'e ) 2 π - 2'
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