69/15 = x And lastly, dividing -69 by 15 gives us.Īlright, so we know that when y is equal to -10, then x is equal to -4.6. 23/3 * 3/5 = x And multiplying this out will give us. 23/3 / 5/3 = x As for the left hand side, we know that dividing by a fraction is the same thing as multiplying by it's reciprocal, so it becomes
23/3 / 5/3 = 5/3x / 5/3 The right hand side cancels out 23/3 = 5/3x, so now we divide both sides by 5/3 So first, we subtract 13/3 from both sides. 10 = 5/3x + 13/3 and from this, we can solve for x in this situation. Now to compare this to when y equal to -10, we would have this:
We also know from the given points that when y equals 6, x is equal to -1. The change in y over the change in x equals out to -10/6, or -5/3. This is seen when you compare the points and the slope. However if Sal were to use -10, the x value he would have to be different. If -10 from the slope were to be a valid option for a point in this equation, that means that the change in x would also have to be the accompanying point on the line to go with the change in y. He could not use -10, because -10 isn't necessarily a point on the line, because it's the change in y. He used 6 because it was one of the points for y on the line.
