# maths

posted by mia

you are at the music store looking for CDs. the store has CDs for \$10 and \$15. you have \$55 to spend. write an equation that represents the different numbers of \$10 and \$15 CDs you can buy.

hmm now.. how do i do this?

1. Reiny

10x + 15y = 55 or
2x + 3y = 11 or 2x = 11 - 3y

now we want only positive integer values of x and y.
clearly x < 6 and y < 4
Furthermore, if y is even, 11 - 3y will be odd, therefore x cannot be an integer.
So y has to be odd, and less than 4

Mmmm now, what do you think?

2. mia

thank you very much!! xx (=

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