00:01
So in problem 1, we have 2x plus y equal to 13.
00:05
So if x is 0, then y is 13.
00:13
If we want y to be 4, then 2x plus 4 is 13.
00:24
That gives me 2x is 9, so x is 9 over 2.
00:29
That one will be 9 over 2.
00:33
Then if we want y to be negative 1, 2x minus 1 equals 13.
00:42
That's 2x equal to 14, so x would then be 7.
00:51
Now let's look at the second problem.
00:54
We have 3x plus 5y equal to 15.
01:00
We want to know what x coordinate goes with a y of 3.
01:05
So 3x plus 5 times 3 is 15.
01:12
That's 3x equal to 0, so x would have to be 0.
01:20
Now if x is 5, then we have 3 times 5 plus 5y is 15.
01:31
So 5y is 0, and then y would be 0.
01:37
Now we want to know the x that goes with negative 3...