



 
Hi Ingrid, At the grade 6 level the best approach is probably the following. You want
which you can restate as
The procedure is then to take integer multiples of 19, subtract from 376 and see if the difference is divisible by 13. To do this in an orderly way you might use a table. Lets call $w$ the integer you multiply by 19.
Thus two rectangles that satisfy the conditions in the problem are one that is 19 cm by 2 cm and the other being 13 cm by 26 cm. To see if this is the only answer you could continue the table.
If you continue to the row with $w = 15$ you will see that there is a second answer. If this problem intrigues you we suggest that you read about Sylvester’s problem. (If a and b are relatively prime natural numbers then every integer greater than (a1)*(b1) can be written as a nonnegative linear combination of a and b.)
We hope this helps,  


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