Out of three given number the first number is twice the second and thrice number is 154 then what is the difference between the first and third number?

Let the third number = N
Then the first number = 3N
And second number = 3N/2
According to the question [N + 3N + 3N/2] / 3=154
⇒ (2N +6N +3N) / 6 = 154
∴ N = (154 x 6) / 11 = 84
∴ Required difference = 3N - N = 2N
= 2 x 84 = 168