21x=14y ==> 7x=4y ===> x=4y/7

Now we have to calculate xy =

I can substitute value of x from above calculated relationship.

I got ==> (4y^2)/7

Now test for given values

A. 14 ===> Y^2 = 14*7/4 = 24.5

B. 28 ===> Y^2 = 28*7/4 = 49 Thus Y=7 answer is B.

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Piyush K

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