Question

Blake has a total of 64 DVD's and CD's. If the number of CD's is eight more than three times the number of DVD's, how many DVD's does he have?

Answer 1

Let x be the number of CDs and y the number of DVDs. Then,\[x+y=64\]\[x=3y+8\]
\[x=64-y\]\[64-y=3y+8\]
\[x=64-y\]\[4y=56\]
\[x=50\]\[y=14\]
So Blake has 14 DVDs.