Cost of a dozen pens (12 pens) = \(₹ 180\)
∴ Cost of 1 pen = \(\frac{180}{12}\)
= 15
Cost of 8 ball pens =\( ₹ 56\)
∴ Cost of 1 ball pen = \(\frac{56}{8}\)
= 7
Ratio of cost of one pen to that of one ball pen = \(\frac{15}{7}\)
\(= 15:7\)
Complete the drawing shown in Fig. 9.14 to indicate where the free ends of the two wires should be joined to make the bulb glow