SOLUTION: A bucket is full of red marbles and white marbles. There are twice as many white marbles as red ones. If I add seven white marbles, there will be three times as many white marbles

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: A bucket is full of red marbles and white marbles. There are twice as many white marbles as red ones. If I add seven white marbles, there will be three times as many white marbles       Log On


   

Question 795432: A bucket is full of red marbles and white marbles. There are twice as many white marbles as red ones. If I add seven white marbles, there will be three times as many white marbles as red ones. How many marbles were in the bucket before the white marbles were added?
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
r for count of red marbles
w for count of white marbles

w=2r, and w%2B7=3r, translated from the description.
You can continue is these make sense; or study and think carefully if they do not make sense.

A change is described for the white marble count which is hypothetical, while no change to the value of the red marble count would happen.

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If you feel good about the system, then simply substitute for w into the plus-seven equation, and solve first for r.
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