If A's income is 12 % more than B's income, B's income is how much less than A's income?

10.70%

Let B's income be ₹100.

Then A's income is 12% more, so:

$A = 100 + 12 = \text{₹112}$

Now, B's income is less than A's by:

$112 - 100 = \text{₹12}$

Percentage by which B is less than A:

$\frac{12}{112} \times 100 = 10.714\% \approx 10.7\%$