In a bag there are 10 to 20 red balls and some balls of other colours. If a ball is taken out randomly, that ball is red $\frac37$ of the time. What is the total number of balls in the bag?
I don't know how this should be done hence I don't have any progress to show. Your hints shall be highly appreciated.
Best Answer
Hint: If we are given that there are $n$ balls in the bag, how many red balls are there?