Sam has a total of 58 DVDs and CDs. If the number of CDs is two more than three times the number of DVDs how many CDs does he have?

Question

anonymous · Answer

no of cds:44
no of dvds:14

anonymous · Answer

Let the number of DVDs be d and the number of CDs be c.
c+d=58
c=2+3d
Solve for c and d.

anonymous · Answer

and how do you do that?

anonymous · Answer

Substitute c=2+3d. Then you can work out d. And then substitute d into c=2+3d.

anonymous · Answer

I still don't understand

anonymous · Answer

I know your supposed to move something around but what?

anonymous · Answer

Now you have two equations:
c+d=58
c=2+3d
If you substitute c=2+3d into c+d=58,
then the first equation will be like:
2+3d+d=58,
which is
4d=58-2=56
So
d=56/4=14