Question

The cost of 5 copies = rs50 then the cost of 9 copies​

Answer 1

$5 \: copies \: =Rs. \: 50 \\ \\ = > 1 \: copy \: = \: Rs. \: \frac{50}{5} \\ \\ = > 9 \: copy \: = \: \frac{50}{5} \times 9 \\ \\ = 10 \times 9 \\ \\ = Rs. \: 90$

I hope this helps.