The cost of 6 pens and 9 pencils is ₹126. What is the cost of 8 pens and 12 pencils?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → ₹168
The two prices cannot be found separately from one equation, but they are not needed: 8 pens and 12 pencils is the same mix as 6 pens and 9 pencils, scaled up. Writing the price of a pen as \(p\) and of a pencil as \(q\):
\(6p+9q=126\), that is \(3(2p+3q)=126\), so \(2p+3q=42\)
\(8p+12q=4(2p+3q)=4\times42=168\)