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Primary 4 | Maths
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Date Posted: 4 years ago
Views: 337
There are a total of 20 notes and their total value is $165.
There is an algebraic method to do this, but it will look alien to you.
Instead, we do guess and check.
Assume, for the start, that all the 20 notes are $10 each. Then, their total value is $200. This is not equal to our wanted $165.
Next, let’s replace one $10 note by one $5 note. The total value of 19 pieces of $10 notes and 1 piece of $5 notes is $195. Basically, by replacing one $10 note with one $5 note, our total value decreases by $5.
Now we replace again one $10 note by one $5 note. The total value of 18 pieces of $10 notes and 2 pieces of $5 notes is $190. Again, this is a decrease by $5.
We continue this until around 13 pieces of $10 notes and 7 pieces of $5 notes for a total value of $165.
There is an algebraic method to do this, but it will look alien to you.
Instead, we do guess and check.
Assume, for the start, that all the 20 notes are $10 each. Then, their total value is $200. This is not equal to our wanted $165.
Next, let’s replace one $10 note by one $5 note. The total value of 19 pieces of $10 notes and 1 piece of $5 notes is $195. Basically, by replacing one $10 note with one $5 note, our total value decreases by $5.
Now we replace again one $10 note by one $5 note. The total value of 18 pieces of $10 notes and 2 pieces of $5 notes is $190. Again, this is a decrease by $5.
We continue this until around 13 pieces of $10 notes and 7 pieces of $5 notes for a total value of $165.
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done
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He used 13 ($10) note and 7 ($5) note. Hope this helps.
Date Posted:
4 years ago
Thx
Tysm
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