Each of the 9 squares shown is to contain one number
chosen from 1, 2, 3, 4, 5, 6, 7, 8, and 9. No number is to
be repeated. Suppose the sum of the 5 squares aligned
vertically on the right is 32 and that the sum of the 5
squares aligned horizontally on the bottom is 20. What
number goes in the shared corner square?  Choose the correct choice from the following options:
A) 3  B) 4  C) 5  D) 6  E) 7

Rationale: if x is the number in the corner square , then the sum of all the numbers in the squares is equal to the sum of the numbers in the five squares aligned vertically plus the sum of the numbers in the five squares aligned horizontally minus x . hence , 1 + 2 + · · · + 9 = 32 + 20 − x . the sum on the left is 45 , so x = 52 − 45 = 7 . correct answer e
Answer: E