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A sum of Rs 800 is in denomination of Rs 10 and Rs 20. If the total number of notes are 50.Find the number of notes of each types. |
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Answer» Step-by-step explanation: Let's call RS. 10 x and Rs. 20 y: x+y= 50 If we subtract y from both sides we get: x= 50-y It makes sense, right? If I take the Rs. 20 notes out of the total of 50 notes, then I am left with just the Rs. 10 notes. So REMEMBER this value of x, we will use it in the next equation: 10x+20y= 800 Now substitute for x: 10(50-y)+20y= 800 500-10y+20y= 800 Subtract -10y+20y on left and subtract 500 on both sides:
10y= 300 y= 30 You have 30 notes of 20 Rs. and: 50-30= 20 notes of 10 Rs. ------------------------ Proof: 30(20)= 600 20(10)= 200 _ _ _ _ ---- Total..: 800 We have the correct answer |
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