In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Q: Problem: average age of students of an adult school is 42 years . 120 new students whose average age is 32 years joined the school . as a result the average age is decreased by 4 years . find the number of students of the school after joining of the new students . 
Options: a ) 1200 , b ) 120 , c ) 360 , d ) 200 , e ) none of these

A: d
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Q: Problem: sum of two numbers is 63 . their difference is 1 / 8 of their sum . their l . c . m is 
Options: a ) 231 , b ) 153 , c ) 351 , d ) 345 , e ) 355

A: c
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Q: Problem: if 5 ^ 21 x 4 ^ 11 = 2 x 10 ^ n . what is the value of n ? 
Options: a ) 11 , b ) 21 , c ) 22 , d ) 23 , e ) 32

A:
b
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