Arif bought 17 pens of three colors- black, green and red. They cost Tk. 5, Tk. 10 and Tk. 25 each respectively. The total amount that Arif paid was Tk. 205. If Arif bought twice as many green pens as red pens, how many black pens did he buy?
বিকল্পসমূহ (নিজের উত্তর যাচাই করতে ক্লিক করুন):
সঠিক উত্তর
1 (5)
বিস্তারিত ব্যাখ্যা ও বিশ্লেষণ:
Solution:
Let,
Arif buys R red pens
Arif buys G green pens
Arif buys B black Pens
If Arif bought twice as many green pens as red pens
∴ G = 2R
Now, B + R + G = 17
⇒ B + R + 2R = 17
⇒ 3R = 17 - B
ATQ,
5B + 10G + 25R = 205
⇒ 5B + 20R + 25R = 205
⇒ 5B + 45R = 205
⇒ 5B + 45{(17 - B)/3} = 205
⇒ 5B + 15(17 - B) = 205
⇒ 5B + 255 - 15B = 205
⇒ 10B = 50
∴ B = 5
