Change in y = 6
change in x = -9
so slope is 6/-9 = 2/-3 =
The total number of calories for 18 cups of milk is 1620 calories.
If two cups of milk is 180 calories then divide 180/2 to find the unit rate.
Then multiply 90 by the number of cups (18) and then you get the total number of calories for that many drinks.
Multiply her answer by -6 and see if the result is -108