In the sample subtraction problem below, single digits are replaced by…

Final digits: A = 7, B = 5, C = 5, D = 2.

Convert the subtraction into an addition to find the digits: A5C1 = 397D + 3B79.

• Units column: D + 9 must end with 1, so D + 9 ≡ 1 (mod 10). The only single-digit solution is D = 2 (2 + 9 = 11), producing a carry of 1.

• Tens column: 7 + 7 plus the carry 1 gives 15, so the tens digit C = 5 and there is a carry of 1 to the hundreds column.

• Hundreds column: 9 + B plus the carry 1 must give the hundreds digit 5. That means 9 + B + 1 = 10 + B = 15, so B = 5 and this produces a carry of 1 to the thousands column.

• Thousands column: 3 + 3 plus the carry 1 equals 7, so A = 7.

So the determined digits are A = 7, B = 5, C = 5, D = 2.

Now evaluate the expression 3*A + A*B + 4*C*D by substituting these values:

• 3*A = 3*7 = 21

• A*B = 7*5 = 35

• 4*C*D = 4*5*2 = 40

Add these results: 21 + 35 + 40 = 96. Therefore the correct value is 96.