The price of an article is marked so as to gain 20%but when a 5% discount allowed in marked price there is profit of rs 4200. find the cost price of the article

30000

Explanation:

here

gain = 20%

also mp is set in such a way that we will gain 20% profit so, by the question

mp=cp+20%of cp

=x (let) + 20%of x

= 120/100x

also, if 5% discount is allowed on mp then rs4200 will be profit., then we have

sp=120/100 x - 5%of 120/100 x

=120/100 x - 600/10000 x

=12000-600/10000 x

=11400/10000 x

=114/100 x

again,

profit = sp - cp

4200=114/100 x - x

4200 = 14x/100 (after taking l. c. m)

x=420000/14 (after cross multiply)

x=rs 30,000