I'm running into a bit of trouble with a question that requires me to calculate the distance between two points on a cartesian graph. The two points are (-5, -5.5) and (-8, 7). In the answer key of my book the equation goes (square root of)(-5-(-14))^2 + (-5.5-3)^2. That's all well and fine, but then they go: (square root of)(5+14)^2 + (-8.5)^2. The -5 in the first equation has become positive and I have no idea why. I don't think it's a typo as if I don't make this change the answer isn't plausable. Could anyone explain this one to me?