Answer
a) The slope represents an increase .02 degrees per year, the T-intercept represents the average surface temperature in 1950.
b) $17$ degrees celsius.
Work Step by Step
a) The equation is a linear one, and linear equation have slopes that represent a constant increase or decrease. .02 is a representation of the average degree increase per year.
Your T-intercept (y-intercept) is always your base number when $x$ or in this case, $t$ equals $0$. This is the starting average surface temperature (1950).
b) $(.02\times100)+15$
(because it's 100 years from 1950)
$2+15=17$
