Question

. A shopkeeper buys 100 pens for 10 each and sells 20 of them at a gain of 10%. What percent he sells the remaining so as to gain 20% in all.​

Answer 1

Answer:

18.75%

Step-by-step explanation:

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Let the 20 pens were sold for "y" each

Total cp = 100*10 = 1000

[(20y-200)/20y ]*100 = 20

20y-200 = 4y

16y = 200

4y = 50

y = 12.5

So, he sold 20 pens in = 12.5*20

= 250

Let the 80 pens were sold for "z" each

So, [{(80z + 250) - 1000}/1000]*100 = 20

Or, 80z + 250 = 1200

80z = 950

z = 11.875

[ (11.875-10)/10 ]*100 = 18.75 %