Finley has 152 yellow, red, and blue marbles in a bag. He has seven more red marbles than yellow marbles, and three times as many blue marbles as yellow marbles. How many yellow marbles does Finley have? Write an equation to represent this problem. Then solve the equation. A. x + x + 7 + 2x = 152; x = 36 B. x + x + 7 + x = 152; x = 48 C. x + x + 7 + 5x = 152; x = 21 D. x + x + 7 + 3x = 152; x = 29