00:01
Okay, so jeff answered all 25 questions on his chemistry test.
00:04
For each right answer, he got four points.
00:05
And for each wrong answer, he lost two points.
00:07
If you got a score of 70 points, how many questions did he get right? so we're going to model this with a system of equations.
00:13
So let's define our variables.
00:15
X is going to be the number of correct questions.
00:22
Y is going to be the number of incorrect questions.
00:30
So the first thing we're going to model is all the questions together.
00:33
The number of correct and incorrect, well, it comes out to 25.
00:37
The second part is if he got four points for every correct question, but he lost two points for every incorrect question...