maths
posted by mia on .
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?

your equation will be
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? 
thank you very much!! xx (=