For this case we have the following variables:
x: the number of minutes of television Sam watched each day
y: the number of minutes she spent exercising
Then, we have the following function that models the problem:
if she spends 30 minutes watching television we have x = 30.
Substituting in the given equation we have:
Answer:
the best prediction for the number of minutes of exercising Sam will do if she spends 30 minutes watching television that day is:
72 minutes