Puzzle | Missing One Rupee I came across the following riddle.

A group of $30$ Indian merchants go to a hotel and stay there for a night. The hotel owner provides for their lunch and breakfast. He serves dinner at the rate of $2$ plates/$\large{₹}$ and breakfast at the rate $3$ plates/$\large{₹}$. When the merchants check out in the morning they are given the bill of $\large{₹}25$ for their food. As per the owner $30$ dinners at the rate of $2$ plates/$\large{₹}$ equals to $\large{₹}15$, and $30$ breakfast at the rate of $3$ plates/$\large{₹}$ equals to $\large{₹}10$, and hence $\large{₹}25$$(10+15)$.
However the merchants give the owner $\large{₹}$$24$ claiming that dinner and breakfast together costed $5$ plates for $\large{₹}$$2$. Therefore, $60$ plates ($30$ of night and $30$ of morning) costs $\frac{2}{5}\times 60 = \large{₹}$ $24$.
Whom do you favor, merchants or the owner, and why?

I am unable to decide who is correct as mathematically they both appear correct to me. Is there a way to find out as to which method is wrong and which is correct one?

The merchants divided 60 plates by 5. They cannot do this, as the 60 has 30 lunch and 30 breakfast while the 5 has 3 plates of breakfast and 2 plates of dinner. 
If the merchants would be correct, 60 divided by these 5 gives 12. Hence there are 12 of such combinations (3 breakfast and 2 lunch) which means that the total number of breakfast should be 12*3=36 and total number of lunch should be 12*2=24. But that is not the case hence the merchants are incorrect. 
