Average salary of Santosh and Renu is Rs 3600. If salary of Santosh and Renu is increased by 50% and 30% respectively, then their total salary is increased by 35%. Find salary of Renu is what percent more or less than salary of Santosh before increment?

The correct option is 200%.

Let the original salary of Santosh be $S$ and the original salary of Renu be $R$.

According to the question, the average salary of Santosh and Renu is Rs 3600.

$\frac{S+R}{2}=3600$

$S+R=7200$    --- (Equation 1)

When the salary of Santosh is increased by 50% and that of Renu is increased by 30%, their total salary increases by 35%.

Increase in Santosh's salary = $0.50S$
Increase in Renu's salary = $0.30R$
Total increase in salary = $0.35(S+R)$

Setting up the equation for total increase in salary:

$0.50S+0.30R=0.35(S+R)$

Simplifying the equation:

$0.50S+0.30R=0.35S+0.35R$

$0.50S-0.35S=0.35R-0.30R$

$0.15S=0.05R$

Dividing both sides by 0.05:

$3S=R$  or  $R=3S$

We are asked to find by what percent the salary of Renu is more than the salary of Santosh before the increment.

Difference in salary = $R-S=3S-S=2S$

Percentage by which Renu's salary is more than Santosh's salary:

$\text{Percentage More}=\left(\frac{R-S}{S}\right)\times 100$

$\text{Percentage More}=\left(\frac{2S}{S}\right)\times 100=2\times 100=200\%$

Hence, the salary of Renu before increment is 200% more than the salary of Santosh.