Answer: Balu originally had 40 sweets.
Explanation:
Let x be the number of sweets Balu originally had.
After Amal gives one third of his sweets to Balu, Balu's number of sweets becomes x + (1/3)x = (4/3)x.
After Balu gives one third of his sweets to Chandran, Chandran's number of sweets becomes 40 + (1/3)(4/3)x = 40 + (1/3)x.
After Chandran gives one third of his sweets to Amal, Amal's number of sweets becomes (2/3)x + (1/3)(40 +(1/3)x) = (2/3)x + (1/3)x + 40/3 = (5/3)x + 40/3.
Since all three of them now have the same number of sweets, we can set the number of sweets each of them has equal:
(4/3)x = (5/3)x + 40/3.
Now, we will isolate x by rearranging the equation. Subtracting (5/3)x from both sides, we get:
(4/3)x - (5/3)x = 40/3
Simplifying the left side:
-x/3 = 40/3
Dividing both sides by -1/3:
x = 40
Thus, Balu originally had 40 sweets.