Given:
Gil buys 4 books for $16. Then he sells 3 CDs for $27.
To find:
The equations for y, Gil’s change in money after buying a book, and for x, his change in money after selling a CD, in standard form.
Slope of each equation.
Solution:
Gil buys 4 books for $16.
4 books = $16
1 book = $4
Let n be the number of book purchased, then change in money after buying n book is
Here, negative sign represents decrease in money. Here, slope of -4 it means the money decreased by $4 after buying each book.
He sells 3 CDs for $27.
3 CDs =$27
1 CDs =$9
Let c be the number of CDs sold, then change in money after selling m CDs is
Here, slope of 9 it means the money increased by $9 after selling each CD.