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Question
primary 5 | Maths
| Whole Numbers
2 Answers Below
Anyone can contribute an answer, even non-tutors.
Please help. Thank you very much
Date Posted: 3 years ago
Views: 527
Excess-shortage
From having $6 left in the first case, to needing $8 more in the second case,
the difference is $8 + $6 = $14
So we can say : for that number of Science books, the same number of Math books will cost $14 more in total.
Since each Math book costs $2 more than each Science book ($9 - $7 = $2)
$14 ÷ $2 = 7
7 Math books cost $14 more than 7 Science books.
This means he wanted to buy 7 books
From having $6 left in the first case, to needing $8 more in the second case,
the difference is $8 + $6 = $14
So we can say : for that number of Science books, the same number of Math books will cost $14 more in total.
Since each Math book costs $2 more than each Science book ($9 - $7 = $2)
$14 ÷ $2 = 7
7 Math books cost $14 more than 7 Science books.
This means he wanted to buy 7 books
He buys 7 Science books and has $6 left.
7 Science books cost : 7 x $7 = $49
$49 + $6 = $55
He has $55
Or
He needs $8 more to buy 7 Math books.
7 Math books cost : 7 x $9 = $63
$63 - $8 = 55
He has $55
7 Science books cost : 7 x $7 = $49
$49 + $6 = $55
He has $55
Or
He needs $8 more to buy 7 Math books.
7 Math books cost : 7 x $9 = $63
$63 - $8 = 55
He has $55
Thank you very much
See 2 Answers
Number of book is same.
Let the number of book = u
If spend on science books,
Total money = $7×u + $6 = 7u + 6
If spend on math books,
Total money = $9×u - $8 = 9u - 8
Therefore
9u-8=7u+6
2u = 14
u = 7
a) Number of books = u = 7 books.
b) Money he have = 7×7 +6 =$55.
Hope this helps.
Let the number of book = u
If spend on science books,
Total money = $7×u + $6 = 7u + 6
If spend on math books,
Total money = $9×u - $8 = 9u - 8
Therefore
9u-8=7u+6
2u = 14
u = 7
a) Number of books = u = 7 books.
b) Money he have = 7×7 +6 =$55.
Hope this helps.
Not sure why a need answer was requested, but this is very correct.
Choo, this is analogous to my explanation. The 'u' you see here is the same as the unknown number of books
Choo, this is analogous to my explanation. The 'u' you see here is the same as the unknown number of books
done
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clear
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Use substitution. Hope that helps!
Date Posted:
3 years ago
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