If the tens digit of positive integer x is 4 and the tens digit of positive integer y is 4, how many possible values of the tens digit of 2(x+y) can there be? Choose the most appropriate option.
A) 2 B) 3 C) 4 D) 5 E) 6
We only need to consider the tens and ones digits of x and y, and the last two digits can be represented as 40 + p and 40 + q respectively.   2(40+p+40+q)= 160 + 2(p + q)   2(p+q) can range from 0 up to a maximum value of 36 when p=q=9.   Then the tens and ones digits of 2(x+y) can range from 60 up to 96.   There can be 4 possibilities for the tens digit.   The answer is 4.
<result>C</result>
If the tens digit of positive integer x is 4 and the tens digit of positive integer y is 4, how many possible values of the tens digit of 2(x+y) can there be?