A box contains $(12+x)$ red balls and $(18+x)$ green balls. A ball is drawn at random and is found to be red. If the probability of drawn ball is $\frac{5}{12}$, then find the value of $x$.

3

A bag contains (12 +x) red and (x + 18)green balls.

The probability of getting a red balls is 5/12.

Probability = Number of observation/Total number of observation

The total number of question = x + x + 12 + 18 = 2x + 30

According to the question:

The probability of getting a red balls is 5/12.

⇒ 12 +x /(2x + 30) = 5/12.

⇒ 144 + 12x  = 10x + 150

⇒ x = 3