Question 53
On the blackboard the multiplication $x \times y$ is written, where $x$ and $y$ are three-digit positive integers. Nicolò, a bit absent-minded, did not notice the multiplication sign and copied into his notebook the six-digit number obtained by juxtaposing $x$ and $y$. The teacher, walking between the desks, points out to Nicolò that the number he wrote is equal to 7 times the product $x y$. What is the sum $x+y$?
(A) 125
(B) 286
(C) 312
(D) 487
(E) 513
(A) 125
(B) 286
(C) 312
(D) 487
(E) 513