The length of a rectangle increases by 15%. Find the percentage decrease in the breadth in order to maintain the area constantly. (Rounded off to 2 decimal places)

Correct option is C

Given:
Length of the rectangle increases by 15%.
Area must remain constant.
Required: Percentage decrease in breadth.
Formula Used:
​$$\text{New Length} = \text{Length} \times \left(1 + \frac{\text{Increase\%}}{100}\right)\\\ \\\text{Area constant} \Rightarrow \text{Length} \times \text{Breadth} = \text{New Length} \times \text{New Breadth}\\\ \\\text{Decrease\%} = \left(1 - \frac{\text{New Breadth}}{\text{Original Breadth}}\right) \times 100\\\ \\$$​​
Solution:
Let original length = L
Let original breadth = B
Original Area = L × B
New Length = 1.15L
Since Area is constant:
L × B = 1.15L × B'
B = 1.15 B'
B' = B / 1.15
B' = 0.869565 B
Percentage decrease in breadth:
​$$\text{Decrease\%} = (1 - 0.869565) \times 100\\= 0.130435 \times 100\\= 13.04\%\\$$​​