12 There are 54 fish in a tank. Some of the fish are white and the rest of the fish are red. Jeevan takes at random a fish from the tank. The probability that he takes a white fish is $\frac{4}{9}$ (a) Work out the number of white fish originally in the tank.

Step 1 ：The problem is asking for the number of white fish in the tank. We know that the total number of fish is 54 and the probability of picking a white fish is \(\frac{4}{9}\).

Step 2 ：We can use these two pieces of information to calculate the number of white fish. The probability of an event is calculated by dividing the number of favorable outcomes by the total number of outcomes.

Step 3 ：In this case, the favorable outcome is picking a white fish and the total number of outcomes is the total number of fish. Therefore, we can set up the equation \(\frac{\text{number of white fish}}{\text{total number of fish}} = \frac{4}{9}\) and solve for the number of white fish.

Step 4 ：By cross multiplying, we get \(\text{number of white fish} = \frac{4}{9} \times 54\).

Step 5 ：Calculating the above expression, we get \(\text{number of white fish} = 24\).

Step 6 ：\(\boxed{\text{Final Answer: The number of white fish originally in the tank is 24.}}\)