00:01
For problem four, we want to write a system of equations.
00:04
We know that two music cds, for this we'll just use a variable c, two music cds, and four dvds.
00:17
For this, we'll use a variable d, come together to cost a total of $40.
00:26
We also know that three music cds and five dvds.
00:34
Dvds come together to cost a total of $55.
00:42
You wanna find the price of each cd and dvd, and we have three options here.
00:49
So what i wanna do is take each of these three options and substitute them into my equations for c and d.
00:57
I'm gonna first start with option one.
01:01
So i'm gonna start with cd being $12 and dvd being $4.
01:05
So if i take 12 and 4 and substitute them into my first equation, i want to see if they will total to equal 40.
01:18
I know 2 times 12 is 24, and i know 4 times 4 is 16.
01:27
I know that 24 plus 16 does give me 40, so that does work...