Option 2 : 1%

**Given:**

Vikash monthly salary first increased by 10 %

Then decreased by 10%

**Calculation:**

Let his salary be 100x

After increasing his salary by 10% will be = 100x × (100 + 10)/100

⇒ 110x

Now, his salary decreased by 10%

So, his salary = 110x × (100 – 10)/100

⇒ 99x

So, the change in his salary = 100x – 99x = x

So, the percentage change of his salary = (x/100x) × 100 = 1%

**∴ The percentage change in monthly salary is 1%**

Formula used:

(a + b + ab/100)%

where a and b = percentage change

when the percentage increased then we will take the +ve sign and when it decreased we will take the -ve sign.

Calculation:

a = 10%

b = -10%

as 10% is decreased

After putting the values of a and b

(10 - 10 - (10 × 10)/100)%

⇒ 1%

∴ The percentage change in monthly salary is 1%