Stream of consciousness rationale: If Selma has fifty marbles, then Merill and Elliot together have 50 - 5 = 45 marbles. We'll assume the number of marbles that Elliot has is x. If Merill has twice as many marbles as Elliot, then the total number of marbles that Merill and Elliot have together is 2x + x = 45 marbles. This translates to 3x = 45. The number of marbles that Elliot has is x = 45 / 3. This means Elliot has x = 15 marbles. Since Merill has twice as many marbles as Elliot, Merill has 2 * 15 = 30 marbles.
The question and answer pair are described below.
Q: Merill has twice as many marbles as Elliot and the two of them together have five fewer marbles than Selma. If Selma has fifty marbles, how many marbles does Merill have?
A: 30