Question

$12$ Copies of book were sold for $Rs.1800$ thereby gaining cost price of $3$ copies. The cost price of a copy of the book is

• A. $Rs.120$
• B. $Rs.150$
• C. $Rs.1200$
• D. $Rs.1500$

Answer 1

The correct option is A $Rs.120$

Let Cost price of $1$ book $=x$

Selling price of $12$ books $=Rs.1800$

Gain $=3x$

Selling price of $12$ book -Cost price of $12$ books = Gain

$1800-12x=3x$

$1800=12x+3x$

$1800=15x$

$x=120$

$\therefore$ Cost of $1$ book $=Rs120$