said by LaZ3R 
:Hmm... Odd, that was a question on the page we got for homework today LOL :)
What school do you go to? :o
Let x = # of $14 books
Let y = # of $19 books
your two equations should be something like this:
x+70=y
14x+19y=17
-------
x+y
Basically 14x+19y(Divided by x+y)=17
And you just substitute from there.
You can also just multiply (x+y) if you move it over to the other side so you'd get: 14x+19y=17(x+y) which is easier to work with :)
I honestly hope your being sarcastic about what school he goes to ....
