A bag contains only red and blue marbles. Yasmine takes one marble at random from the bag. The probability that she takes a red
marble is 1 in 5. Yasmine returns the marble to the bag and adds five more red marbles to the bag. The probability that she takes one red marble at random is now 1 in 3. How many red marbles were originally in the bag?
Sure! So you need to make an addition problem, for example, 200+25; that equals 225, right? Now you need to subtract from 225. For example, 225-10= 215. Hope I helped!
