If x and y are positive integers such that y is a multiple of 5 and 3x + 8y = 500, then x must be a multiple of which of the following?  Options:	A) 3.	B) 6.	C) 7.	D) 8.	E) 10.
If y is a multiple of 5, then 8y is also a multiple of 5.   3x = 500 - 8y   500 - 8y is even and it is a multiple of 5.   Thus x must also be even and a multiple of 5.   Therefore x must be a multiple of 10.   The answer is 10..
<result>E</result>
If x and y are positive integers such that y is a multiple of 5 and 3x + 8y = 500, then x must be a multiple of which of the following?