00:03
Right, we're told that a plane can fly 1 ,072 miles in four hours with the wind at its back, basically, helping push it along, and only 848 miles in the same four hours when it's against the wind.
00:18
All right, well, i'm going to start, and we're, of course, asked how fast is the plane, what is the wind speed, things like that.
00:25
So what i always start with in these problems is distance equals break times time.
00:29
It's one of our most basic formulas.
00:31
So i'm going to go ahead and substitute in my two equations here.
00:35
So the distance, well, for the first one, it's 1 ,072 miles, equals the rate.
00:41
Well, i don't know what the rate is.
00:44
And we're adding the wind speed to it this time.
00:48
And that's going to be multiplied by four.
00:50
All right.
00:51
So there's my first equation.
00:53
The second equation, well, my distance is 848, and that's equal to.
01:01
Well this time it's the rate we have to subtract the wind all right and that's also times four in this case all right so now i have my two separate equations and i should be able to solve for each of the two variables that i have all right probably first thing i would do is just divide both sides by four so 107 -2 when we divide that by four is two hundred and sixty -eight so this is my first equation, the one in red.
01:32
So 268 is equal to r plus w.
01:37
All right.
01:38
And i probably don't even need a calculator for this blue one.
01:41
When i divide both sides by four, goes in to 112, 212, and that's equal to r minus w...