The values are always interpreted as (x1, y1) and (x2, y2) in order from left to right, so in this case, (7,2) are (x1, y1) and (15, 8) are (x2, y2)
Well, there are 3 feet in 1 yard, and 1.09 yards in 1 meter, so then

notice, we use the ratio, and whichever unit you want cancelled, you simply flip the ratio to have it cancelled, if the "m" is atop and you need that cancel, use the ratio with the "m" at the bottom, m/m = 1, and so they cancel out, and so on.
Answer:
To produce 400 gallons of a chemical, it costs 700 dollars.
Step-by-step explanation:
We have that:
The cost, C (in dollars) to produce g gallons of a chemical can be expressed as C=f(g).
The interpretation is:
To produce g gallons of a chemical it costs C dollars.
So
f(400)=700
This means that to produce 400 gallons of a chemical, it costs 700 dollars.
Subtract -6 on both sides
Now you have x/-2 on the left and 3 on the right
Then multiply -2 on both sides, leaving you with x on the left and -6 on the right
So x< -6