Description for Correct answer:
Let time taken by B to fill the tank, a = xh.

Therefore, Time taken by A to fill the tank

b = \( \Large x+\frac{x \times 80}{100}=\frac{9x}{5}h \)

According to the formula,

Time taken by both the taps to fill the tank

\( \Large t = \frac{ab}{a+b} \)

=> \( \Large 45 = \frac{x \times \frac{9x}{5}}{x+\frac{9x}{5}} \)

=> \( \Large 45 \times \frac{14x}{5}=\frac{9x^{2}}{5} \)

Therefore, x = \( \Large \frac{45 \times 14}{9} \)