Concept: The question tests on the basics of Number Properties
Solution:
Given 3x = 200 -4y
=> 3x = Difference of even numbers = even
=> As 3 is odd x must be even (So A & C eliminated)
Also it is a difference of multiples of 5 => 3x is also a multiple of 5
=> x is a multiple of 5 as 3 is not =>So 10
(option e)