Discussion

If 12 - 9 = 63, 10 - 7 = 51, 14 - 12 = 52, then 15 - 5 = ?

Answer: C

The answer is 200.

Each result is the sum of the two numbers multiplied by their difference:

\[ \begin{aligned} (12+9)(12-9) &= 21 \times 3 = 63 \\ (10+7)(10-7) &= 17 \times 3 = 51 \\ (14+12)(14-12) &= 26 \times 2 = 52 \end{aligned} \]

\[ (15+5)(15-5) = 20 \times 10 = 200 \]

44, 100 and 625 do not fit the rule; 100 is just \(10^{2}\), the square of the difference.

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