David bought 3 DVDs and 4 books for $40 at a yard sale. Anna bought 1 DVD and 6 books for $18. How much did each DVD and book cost?
1 Answer
Apr 19, 2017
A book is 12 times cheaper than a DVD
Explanation:
Your equations (2 unknowns and two equations, d is for a DVD and b is for a book):
For David:
For Anna:
Now multiply the second equation with -3 and add to the first equation:
Combined equation:
Now for DVD price, use the second equation:
A book worths $1 and a DVD worths $12.