The selling price of 30 books is equal to the cost price of 45 books. Find the loss or gain percentage.

Correct option is A

Given: 

Selling Price(SP) of 30 book = Cost Price(CP) of 45 Books 

Formula Used: ​

Loss and gain % = $$\frac{\text{Loss or Profit} }{CP}\times 100$$ 

Solution:  

SP of 30 = CP of 45 

​$$\frac{SP}{CP} = \frac{45}{30} \\ \ \\ \frac{SP}{CP} = \frac{3}{2}$$ 

SP >CP 

So, 

Profit % = $$\frac{3-2}{2} \times 100 = 50\%$$​​