 In this video, we provide the solution to question number 15 for the practice final exam for math 1050. We are given a 2 by 2 system of linear equations. We have 3x minus y equals 12 and 7x plus 2y equals 30. So suppose we want to solve this system of equations using the substitution method. What would be the best approach here? Well, substitution, we have to solve for one of the variables. We have to either solve for x or solve for y in one of the equations there. And when I say the best method here, what's going to be the easiest for us to do this by hand? Now, if you try to solve for x in the first equation, I mean, you could do that. You could divide by 3. 3 does go on to 12 four times. That would be okay. When it comes to y, you can just move the y to the other side and move the 12 over here. There's no division whatsoever, so I like that one. That's my contender so far. If you try to solve for x, you divide by 7, you're going to get like some fractions 30 over 7, 2 over 7. That's going to be a nightmare. And then the last one here, if you could solve for y, you'd have to divide by 2. But again, you get some fractions in that situation there. And I should mention that when you're solving for x, you get a 1 third in front of the y. We divide by it. So honestly, the only one that doesn't lead to fractions would be solving for y right here. So really, the best one that would lead to the easiest calculations, the fastest one, would be to solve for y inside of the first equation.