chetan2u wrote:
Bunuel wrote:
If the tens digit of the positive integer x and the tens digit of the positive integer y are both 6, what is the number of different possible values for the tens digit of 2x + 2y?
A. Three
B. Four
C. Five
D. Six
E. Seven
A. Three
B. Four
C. Five
D. Six
E. Seven
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Screenshot 2024-01-02 202125.png
The tens digit of 2x+2y will depend only on the units digit, so it doesnt matter what other digits are.
Let the two numbers be 6a and 6b.
Least value of 2(x+y) = 2(60+60) = 240
Maximum value of 2(x+y) = 2(69+69) = 276
So 2(x+y) can take all even values from 240 to 276.
Thus, tens digit can be 4, 5, 6 and 7, a total of four values.
B
What do you mean by even values? Also why is the assumption that the "positive" integer for x and y is only 2 digits (and not bigger)? Help is appreciated
