Math, asked by sathishamd1, 2 months ago

26) A girl purchased certain of number of pens for 40. She kept 5 pens for herself and sold
the remaining for 1 rupee more for each there by gaining Rs. 10 on the whole. Find the
number of pens bought by her.

Answers

Answered by XxItzYourBabyxX

Answer:

sʜᴇ ʙᴏᴜɢʜᴛ 9 ᴘᴇɴs.

Step-by-step explanation:

let the number of pens be x

certain pens cost = rs 40

she kept 5 pens = x-5

She gain by selling = Rs 10

Number of pens she bought

= 10(x-5)=40

= 10x-50=40

= 10x = 40+50

= 10x= 90

= x = 90/10

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Answered by Swarup1998

She bought 35 pens.

Correct question:

A girl purchased certain number of pens for Rs. 140. She kept 5 pens for herself and sold the remaining for 1 rupee more for each thereby gaining Rs. 10 on the whole. Find the number of pens bought by her.

Step-by-step explanation:

Let the number of pens bought by her is x.

Given, cost price of x number of pens is Rs. 140

Then cost price of each pen

= Rs. 140/x

Selling price of each pen

= Rs. (140/x + 1)

She kept 5 pens for herself. So (x - 5) pens remain. Selling price of (x - 5) number of pens

= Rs. (x - 5) * (140/x + 1)

According to the question, selling price of x number of pens = Rs. 10 gain on the whole

➜ (x - 5) * (140/x + 1) = 140 + 10

➜ (x - 5) (140 + x)/x = 150

➜ (x - 5) (140 + x) = 150x

➜ 140x + x² - 700 - 5x = 150x

➜ x² - 15x - 700 = 0

➜ x² - 35x + 20x - 700 = 0

➜ x (x - 35) + 20 (x - 35) = 0

➜ (x - 35) (x + 20) = 0

Either x - 35 = 0 or, x + 20 = 0

➜ x = 35 or, x = - 20

Since x > 0, x = 35

∴ she bought 35 pens.