The sum of 3 numbers is 198.If the first number is 1/3rd of the second number and the third number is 5/7th of the first number, then what is the difference between the first number and second number?

Let's denote the three numbers as A, B, and C.

From the problem, we know that:

A + B + C = 198

We also know that:

A = B/3

And:

C = 5A/7

We can substitute A and C in the first equation with their equivalents in terms of B:

B/3 + B + 5(B/3)/7 = 198

Solving this equation for B gives us:

B = 126

Substituting B = 126 into A = B/3 gives us:

A = 126/3 = 42

The difference between the first number (A) and the second number (B) is:

B - A = 126 - 42 = 84

Let's denote the three numbers as A, B, and C.

According to the problem, we have the following relationships:

1. A + B + C = 198
2. A = B/3
3. C = 5A/7

We can substitute the second and third equations into the first one to solve for the variables:

Substituting A = B/3 into the first equation, we get B/3 + B + C = 198.

Substituting C = 5A/7 into the equation above, we get B/3 + B + 5(B/3)/7 = 198.

Solving this equation for B, we get B = 84.

Substituting B = 84 into A = B/3, we get A = 28.

So, the difference between the first number (A) and the second number (B) is 84 - 28 = 56.