Step 1:

(a)

The expression is

The above expression is in the form of slope-intercept equation .

Where m represents slope and b represents y-intercept.

Compare the expression with slope-intercept form :

Slope is 0.02.

T - intercept is 8.50.

Here slope represents the rate of change of temperature with respect to time is 0.02

         T - intercept represents that the temperature is in 1900.

Step 2 :

(b)

represents years since 1900.

Average global surface temperature in 2100 (After 200 years) means 

Substitute in T:

The temperature for the year 2100 is  

Solution: 

(a) Slope represents the rate of change of temperature with respect to time is 0.02.

     T - intercept represents that the temperature is when time is zero.

(b) Average global surface temperature in 2100 is .