Answer 4) (Y-1)/(Y+G-1) is the correct answer.

Understanding algebraic equations is essential to your success on this problem.

          The problem offers no specific number of marbles of either color, only that the marbles are either yellow (Y) or green (G).

Therefore, you are working exclusively with variables.

• Total number of yellow marbles = Y

• Total number of green marbles = G

• Total marbles = Y + G

          Taking out only 1 yellow marble effects two different numbers

• Number of yellow marble(Y) in the bag is now (Y-1); one less than before

• Number of total marbles (Y + G) in the bag is now (Y + G -1); one less than before

          The fractional portion of yellow marbles at the start, regardless of how many was       

(Y)/(Y + G).

 Since each is reduced by one marble

(Y – 1)/(Y + G – 1)