Question

The cost price of 10 articles is equal to selling price of 9 articles.find the profit percent?

Answer 1

Let sell price of one article is S
Let cost price of one article is C

Then 10C = 9S
so, C = 9S / 10

Thus profit on one article P = S - C
P = S - (9S / 10)
P = S / 10
P/S = 1/10

%profit = (P/S) × 100
%profit = 10%

Answer
10%

Answer 2

C10=S9
C=S9/10
P =S-C
P=S-S/910
P=S/10
P/S=1/10
P%=1/10*100
P=10