CEMC Fermat, 1998

Combinatorics Difficulty 2.0 Junior Find the answer Canada

The number in an unshaded square is obtained by adding the numbers connected to it from the row above. (The '11' is one such number.) The value of $x$ must be

(A) $4$ (B) $6$ (C) $9$ (D) $15$ (E) $10$

Figure for this problem

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