Please help me calculate the answer to the question:

S2 died May 12, 2015, and the trusts had the following values (assumes estate tax at S1's death is allocated between Trusts B & C in proportion to pre-tax funding values and 40% appreciation in value):

Trust A: $3,360,000 Trust B: $4,239,679 Trust C: $7,086,321

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THIS IS THE QUESTION BELOW:

Determine the federal estate tax before considering the PTC.