Respuesta :
					                   In this case the temperature depends on the hour.  So temperature is your X and hour is your Y variable.  When h=0, x=0.   So the 21*C is you x=0 or y-int point.  
If we are trying to match the equation for a line of y=mx+b, 21*C=b.
Our rate of change is -4*C/h, which is our m variable.
So y=(-4)x+(21)
OR in this case, t=-4h+21.
Answer D.
					                
					             If we are trying to match the equation for a line of y=mx+b, 21*C=b.
Our rate of change is -4*C/h, which is our m variable.
So y=(-4)x+(21)
OR in this case, t=-4h+21.
Answer D.
 
			                  