Question 1152863
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<font color=blue>A box of sweets is shared between A B C in the ratio of 3:4:5</font>, so this means 
A recieves 3/12 of the total
B recieves 4/12 of the total
C recieves 5/12 of the total
note that 3+4+5 = 12


Since B got 48 pieces, and B got 4/12 of the total, we know that,
x = total number of candies
B = amount B gets
B = (4/12)*x
48 = (4/12)*x
(4/12)*x = 48
(1/3)*x = 48
x = 3*48
x = 144
There are 144 candies total.


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Now turn to the information that the ratio of A:B:C updates to 12:16:15 after C shares his some of sweets.


This means,
A receives 12/43 of the total
B receives 16/43 of the total
C receives 15/43 of the total
we have 12+16+15 = 43 


Assuming the total has not changed, then,
A = (12/43)*x
A = (12/43)*144
A = 40.186046511628
But this is not a whole number


So it is possible that your teacher made a typo when coming up with the ratios. 
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