A boy aged 12 years is left with Rs. 100000 which is under a trust. The trustees invest the money at 6% per annum and pay the minor boy a sum of Rs. 2500, for his pocket money at the end of each year. The expenses of trust come out to be Rs. 500 per annum. Find the amount that will be handed over to the minor boy after he attains the age of 18 years ?

$$\eqalign{ & {\text{Sum of the 12 years age }} \cr & {\text{ = Rs}}{\text{. 100000}} \cr & {\text{Sum of the 18 years age }} \cr & = {\text{P}} + \frac{{{\text{P}} \times {\text{R}} \times {\text{T}}}}{{100}} \cr & = {\text{100000}} + \frac{{100000 \times 6 \times 6}}{{100}} \cr & = {\text{100000}} + {\text{36000}} \cr & = {\text{136000}} \cr} $$
Total expenses
= 2500 + 500 = 3000 per year
Total expenses ( 6 years )
= 3000 × 6 = Rs. 18000
Amount obtained
= 136000 - 18000
= 118000