Let y be the temperature x hours after midnight. the temperature is 60°f at midnight and decreases 2°f every 1/2 hour.

In this item, it is assumed that we are to establish or generate the equation for the temperature of the surrounding x hours after midnight. 

From the given above, the slope of the equation should be -2 since the temperature decreases by this rate. Also, the y-intercept is equal to 60 since this is the initial value. The equation is then,
 
      y = (-2)(1/2)(x) + 60