Difference between revisions of "1997 PMWC Problems/Problem I6"
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| − | < | + | == Problem == |
| + | John and Mary went to a book shop and bought some exercise books. They had <math>\</math>100 each. John could buy 7 large and 4 small ones. Mary could buy 5 large and 6 small ones and had <math>\</math>5 left. How much was a small exercise book? | ||
| + | |||
| + | |||
| + | == Solution == | ||
| + | <math>7l+4s=100</math> | ||
| + | |||
| + | <math>5l+6s=95</math> | ||
| + | |||
| + | <math>2l-2s=5</math> | ||
| + | |||
| + | <math>6s-6l=-15</math> | ||
| + | |||
| + | <math>11l=110</math> | ||
| + | |||
| + | <math>l=10</math> | ||
| + | |||
| + | <math>s=\dfrac{15}{2}</math> | ||
| + | |||
| + | Plugging them back in, we see that they work. | ||
| + | |||
| + | == See also == | ||
| + | {{PMWC box|year=1997|num-b=I5|num-a=I7}} | ||
| + | |||
| + | [[Category:Introductory Algebra Problems]] | ||
Revision as of 18:20, 8 October 2007
Problem
John and Mary went to a book shop and bought some exercise books. They had 
100 each. John could buy 7 large and 4 small ones. Mary could buy 5 large and 6 small ones and had 5 left. How much was a small exercise book?
Solution
Plugging them back in, we see that they work.
See also
| 1997 PMWC (Problems) | ||
| Preceded by Problem I5 |
Followed by Problem I7 | |
| I: 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 T: 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 | ||
