164
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We have two crucial pieces of information:
1. If you transfer 100 pebbles from pile A to pile B, the number of pebbles in pile B becomes twice the number of pebbles in pile A.
This can be written as the following equation:
2. If you transfer 1 pebble from pile B to pile A, the number of pebbles in pile A becomes six times the number of pebbles in pile B.
This can be written as the following equation:
We can substitute the value of B from equation 1 into equation 2:
Therefore, pile A has at least 164 pebbles.