You could use a thermometer on a pets fur if it was outside or measure the amount of air in a ball since air is heated it expands there for making the ball have more air? it’s a long shot but i would just go for the first idea to be honest
5-7 = -2 and 1-6= -5 so the slope would be 2/5. you would set it up like this:
y=2/5x and then your y-intercept
The answer is B) 20 lbs for $22 because carol is getting 8 pounds more for only $9+