Step 1: Set up the salaries and note what stays the same.
Let the original salaries be \( 2k \) and \( 3k \), so the difference between them is \( 3k - 2k = k \). Adding Rs. 4000 to both salaries does not change this difference, since the same amount is added to each.
Step 2: Write the new salaries using the new ratio.
The new ratio is 40:57, so the new salaries can be written as \( 40m \) and \( 57m \) for some number \( m \), and their difference is \( 57m - 40m = 17m \). Since this difference must equal the unchanged difference \( k \) from Step 1, we get \[ k = 17m \]
Step 3: Use the larger new salary to solve for m.
Jimmy's new salary is the larger one, \( 3k + 4000 \), which also equals \( 57m \). Substituting \( k = 17m \): \[ 3(17m) + 4000 = 57m \] \[ 51m + 4000 = 57m \] \[ 4000 = 6m \] \[ m = \frac{4000}{6} \]
Step 4: Find Jimmy's original salary.
Jimmy's new salary is \( 57m = 57 \times \frac{4000}{6} = 38000 \). Since this is Jimmy's salary after adding Rs. 4000, the original salary is \[ 38000 - 4000 = \boxed{34000} \]