00:01
We've got a number line here that shows the effect of different activities on someone's lifespan.
00:06
So we're going to use that number line to answer the question, what's the difference in the lifespan between someone who has less than 12 years of education and someone who smokes cigarettes? so first we're going to find those two events on the timeline.
00:21
Somebody with less than 12 years of education is right here at negative 5.
00:25
Someone who smokes is here at negative 9.
00:28
So if we want to find the difference in those two, difference is going to mean subtraction.
00:33
So you're going to subtract those two numbers.
00:37
So we'll do negative 5 minus negative 9.
00:43
We can rewrite this subtraction as an addition problem.
00:47
Sometimes it's easier to look at something as addition instead of subtraction.
00:51
And the way you do that is you add the opposite of the second number.
00:55
So negative 5 stays in negative 5 and we'll add positive 9...