Newaz111 wrote:The sum of positive integers x and y is 77. What is the value of xy?
(1) x = y + 1
(2) x and y have the same tens digit.
Statement 1:
Since x+y = 77 and x-y = 1, we have two variables and two distinct linear equations, allowing us to solve for x and y.
Thus, the value of xy can be determined.
SUFFICIENT.
Statement 2:
Since 29+29 = 48 and 39+39 = 78 -- and the sum of x and y is BETWEEN 48 and 78 -- the tens digit for x and y must be 3.
Since 39+39 = 78, and the desired sum for x and y is ONE LESS than 78, either x or y must be ONE LESS THAN 39.
If x=38 and y=39, then xy = 38*39.
If x=39 and y=38, then xy = 39*38.
Since the product is the same in each case, SUFFICIENT.
The correct answer is
D.
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