00:03
Okay, we know that water freezes at 0 degrees c, and that's the same as 32 degrees f, and water boils at 100 degrees c celsius, and that's the same thing as 220 degrees f or fahrenheit.
00:19
So let's write an equation that relates c and f.
00:22
So our points here will be in the form, cf, and we have 0 is 32, and 100 is 2112.
00:37
So first we need to find the slope.
00:43
Y minus y, but f is being y here.
00:46
Because it's over in the right hand side, 212 minus 32 over 100 minus 0.
00:55
That's 180 over 100, which reduces to 9 5ths, 9 5ths equal.
01:07
And i'm going to go ahead and put it f here because the top row is f and is 32 over c minus 0.
01:18
Okay, now you can simplify this however you want.
01:20
I'm going to cross multiply like usual, and i get 9c equals 5f minus 160.
01:29
All right, so now you can either solve it for c, solve it for f, or put it in standard form where c and f are on the same side.
01:37
That's what i'm going to do.
01:38
And the reason i'm going to do that is because they're going to give us numbers to plug in that are both c and f.
01:44
All right, so we're going to fill out this chart and we're given c and f, 0 degrees and minus 10 degrees and 10 degrees, 68, 90, and 177.
02:09
Okay, so the first one, if f is zero, we get 9c minus 0 equals minus 160, z is, z is, negative 160 over 9 which is about negative 18...