If the discount on Rs. 498 at 5% simple interest is Rs.18, when is the sum due?

F = Rs. 498
TD = Rs. 18
PW = F - TD = 498 - 18 = Rs. 480
R = 5%

$TD=\frac{PW\times TR}{100}$

$\Rightarrow 18=\frac{480\times T\times 5}{100}$

=> T = 3/4 years = 9 months