Each tin now has an equal number of cookies.

Number of cookies in each tin now
= 186 ÷ 3 = 62

Now look at the overall change in the number of cookies for each tin.


Tin C :

25 cookies added in (from Tin B)
30 taken out ( to put into Tin A)

Net change : 25 - 30 = -5
Number of cookies decreased by 5.

So number of cookies in Tin C at first
= 62 + 5
= 67


Tin B :

22 cookies added in (from Tin A)
25 taken out ( to put into Tin C)

Net change : 22 - 25 = -3
Number of cookies decreased by 3.

So number of cookies in Tin B at first
= 62 + 3
= 65


Tin A :

22 taken out ( to put into Tin B)
30 cookies added in (from Tin C)

Net change : 30 - 22 = 8
Number of cookies increased by 8

So number of cookies in Tin A at first
= 62 - 8
= 54