SOLUTION: a jar contains 20 white marbles,30 black and some red marbles. half of the marbles are black faind ratio of the white to red marbles. how many marbles are in the jar? how c

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Question 692703: a jar contains 20 white marbles,30 black and some red marbles. half of the marbles are black faind ratio of the white to red marbles.

how many marbles are in the jar?

how can u find the number of red marbles?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Half the marbles are black; you need to know how many marbles are red.

x=Number of Red Marbles.

Total count of marbles = 20 + 30 + x
30 = Count of the black marbles.

Half the marbles are black:
30%2F%2820%2B30%2Bx%29=1%2F2
20%2B30%2Bx=60
highlight%28x=10%29 red marbles.