Probability question ???

A bag contains red and blue balls. Sam chooses a ball at random. The probability that the ball is red is 1/5. 7 balls are added to the bag and the pro

A bag contains red and blue balls. Sam chooses a ball at random. The probability that the ball is red is 1/5. 7 balls are added to the bag and the probability of choosing a red ball is now 1/4, how many blue balls are in the bag ?

Can you provide answer with detail work out please?

or:A bag contains red and blue balls. Sam chooses a ball at random. The probability that the ball is red is 1/5. 7 balls are added to the bag and the probability of choosing a red ball is now 1/4, how many blue balls are in the bag ?Can you provide answer with detail work out please?

Tags:blue,probability,