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: a & b started a partnership business . a ' s investment was thrice the investment of b and the period of his investment was two times the period of investments of b . if b received rs 4500 as profit , what is their total profit ? 
Options: a ) 28000 , b ) 30000 , c ) 31500 , d ) 34000 , e ) none of these

A: c
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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: how many kg of pure salt must be added to 100 kg of 10 % solution of salt and water to increase it to a 20 % solution ? 
Options: a ) 6.7 , b ) 1.3 , c ) 9.6 , d ) 12.5 , e ) 7.9

A:
d
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