At first it increased by 25% and then decreased by 40%

12%

Step-by-step explanation:

Let the original salary be Rs a

Salary after increase = a + 40% of a

= a + 40a/100

= 140a/100

= 14a/10

= 7a/ 5

Salary after Decrease = 7a/5 - 20% of 7a/5

= 7a/5 - 20× 7a / 100 × 5

= 7a/5 - 7a/25

= ( 35a - 7a) / 25

= 28a/25

Absolute increase = 28a/25 - a

= 3a/25

Percentage = 3a/25 ×100 / a

= 3 × 4

= 12%