Question

rao bought notebooks at the rate of 4 rupees 35 man sold them at the rate of 5 for 58
calculate his gain percent and the number of books you should sell to earn a profit of 171

Answer 1

gain percent  =   (selling price - cost price )/cost price  * 100
            = (5.58 - 4.35)/4.35 * 100  = 28.27 %

profit needed = 171
let number of books be = n
profit = n * (selling price - buying price) = 171
              n = 171/1.23 = 139  approx.

gain %:     171/(139 * 4.35)  * 100  = 28.28 %

Answer 2

4 notebooks cp =rs.35

1 notebook cp. =rs.35/4

=rs.8.75

5 notebooks sp. =rs58

1 notebook sp. =rs.58/5

=rs. 11.6

profit =11.6-8.75

=2.85

profit percent=285/875*100

=228/7%