Question: Mary and her two friends came up with the idea of collecting marbles each day for their play on weekends. From Monday to Friday, Mary collected twice as many red marbles as Jenny and half the number of blue marbles collected by Anie, who collected 20 more red marbles than Mary and twice the number of blue marbles Jenny collected. If Jenny collected 30 red marbles and 25 blue marbles, what's the total number of blue marbles collected by the friends together? Think carefully first, then make a decision:
If Mary collected twice the number of red marbles collected by Jenny, she got 2 * 30 = 60 red marbles. Anie collected 20 more red marbles than Mary, which is 60 + 20 = 80 red marbles. The total number of red marbles is 60 + 80 + 30 = 170 red marbles. If Anie collected twice the number of blue marbles collected by Jenny, then she got 2 * 25 = 50 blue marbles. Mary collected half the number of blue marbles collected by Anie, thus 1 / 2 * 50 = 25 marbles. The total number of blue marbles collected is 50 + 25 + 25 = 100 blue marbles. So the answer is 100.