A shopkeeper bought 300 eggs at 80 paisa each. 30 eggs were broken in transit and then he sold the remaining eggs at one rupee each. Find his gain or loss as percent.

C.P. of 1 egg = 80 paisa

C.P. of 300 eggs = 300 x $\dfrac{80}{100}$

= 300 x $\dfrac{4}{5}$

= $\dfrac{1,200}{5}$

= ₹ 240

S.P. of 1 egg = ₹ 1

Total number of eggs = 300

Broken eggs = 30

Remaining eggs = 300 - 30 = 270

S.P. of 270 egg = 270 x ₹ 1 = ₹ 270

(∵ S.P. is greater than C.P.,means eggs are sold at gain.)

Gain = S.P. - C.P.

= ₹ 270 - ₹ 240

= ₹ 30

$\text{Gain\%} = \dfrac{\text{Gain}}{\text{C.P.}} \times 100\%\\[1em] = \dfrac{30}{240} \times 100\%\\[1em] = \dfrac{1}{8} \times 100\%\\[1em] = \dfrac{100}{8}\%\\[1em] = 12.5\%$

Hence, Gain% = 12.5%