Answer:
The answer is b. 4*3 2/5.
Step-by-step explanation:
It states 4 times the amount Ruby mixed. Ruby mixed it 3 2/5 solution. So you would right out 4 x 3 2/5.
The total number of marbles is 30+20+50= 100, so. Since there are 20 red marbles and 50 blue marbles. There are 30+50=80. 80/100=4/5= 80%