Given :
Nathan smiled at 50 people one day and recorded that 36 people smiled back at him.
To Find :
How many people should Nathan expect to return a smile if he smiles at 650 people over a period of time.
Solution :
Ratio of people smiled by total number of people is :

Now, it is given that we have to use the given conditions.
Therefore, ratio will be same :

Therefore, number of smiles Nathan expect to return is 468.
y= -1x -3
that's equation of the line
Y=68+4x
100=68+4x
-68=-68
32=4x
Divide both sides by 4
x=it will take 8 min. for the water to reach 100 degrees
y=total degrees
x=# of minutes