$34.5 \% \text{ of } 1800 + 12.4 \% \text{ of } 1500 = (?)^3 + 78$

If $20 \%$ of $a = b$,then $b \%$ of $20$ is the same as: (in $\%$ of $a$)

The length of a rectangle increases by $20 \%$ and the breadth by $30 \%$. Then the perimeter of the rectangle will increase by:

Depreciation applicable to an equipment is $20 \%$. The value of the equipment $3$ years from now will be less by: (in $\%$)

$0.005 = (-?-)*$

$A$ man's annual income has increased by ₹ $5$ lakhs,but the tax on income that he has to pay has reduced from $12 \%$ to $10 \%$. He now pays ₹ $10,000$ more income tax. What is his initial income (in ₹ lakhs)?