A certain number of capsule were purchased for Rs. 176. Six more capsule could have been purchased in same amount if each capsule were cheaper by Rs. 3. What was number of capsules purchased?

Let Price of each capsule were Rs. X, originally.
So, Number of capsule purchased originally,
= $$ \frac{{176}}{{\text{X}}}$$
If price of capsule is Rs. 3 less then 6 more capsule were purchased. In this case, the number of capsules,
= $$ \frac{{176}}{{{\text{X}} - 3}}$$

According to question,
$$\eqalign{ & \frac{{176}}{{{\text{X}} - 3}} - \frac{{176}}{{\text{X}}} = 6 \cr & \frac{{176{\text{X}} - 176{\text{X}} + 528}}{{{\text{X}} \times \left( {{\text{X}} - 3} \right)}} = 6 \cr & 6{{\text{X}}^2} - 18{\text{X}} - 528 = 0 \cr & {{\text{X}}^2} - 3{\text{X}} - 88 = 0 \cr & {{\text{X}}^2} - 11{\text{X}} + 8{\text{X}} - 88 = 0 \cr & \left( {{\text{X}} - 11} \right)\left( {{\text{X}} + 8} \right) = 0 \cr} $$
Either,
X = 11
Or, X = -8 (Price cannot be negative)
Thus, X = Rs. 11 Hence,
Number of the capsule purchased = $$\frac{{176}}{{11}}$$ = 16