SOLUTION: A jar contains 10 red marbles and 30 green ones. How many more red marbles must be added to the jar so that 60% of the marbles will be red?

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Question 319040: A jar contains 10 red marbles and 30 green ones. How many more red marbles must be added to the jar so that 60% of the marbles will be red?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
The ratio of red to the total is R%2F%28R%2B30%29 where R is the number of red marbles.
R%2F%28R%2B30%29=60%2F100
100R=60%28R%2B30%29
100R=60R%2B1800
40R=1800
R=45
You need to have 45 marbles in the jar to have 60% red.
You currently have 10 marbles.
N=45-10=35
You need to add highlight%2835%29 red marbles.