Question

a dealer allows a discount of 10% and still gains 5%. What percent above the cost price must he mark his goods?

Answer 1

Follow the attachment

Answer 2

Let the shop keeper marks his good by x % above the cost price.

Suppose the cost price(C.P.) of the good be Rs p.

Marked price of the good = Rs p + x % of Rs p = Rs p +Rs. x/100=Rs.p(1+x/100)

Given , Discount = 10 %

Discount on the good = 10 % of  Rs. p(1+x/100)

=10/100*Rs. p(1+x/100)

=Rs. p/10(1+x/100)

Selling price of good, S.P.

= Marked price of the good – Discount on the good

=Rs. p(1+x/100)-Rs. p/10(1+x/100)

Gain = S.P. – C.P.
={Rs. p(1+x/100-Rs. p/10(1+x/100)}-Rs. p

*the image will be stage in this line

Thus, the shopkeeper marks his good above the cost price by
50/3%