The y-intercept is the starting point. Since the temperature started at -7, we know that b in y = mx + b has to be -7. m is the slope which in our case is 3 because the temperature is changing every hour. So, because the temperature is going up, it's +3. Our equation should be y = 3x - 7.
For the letter a it is x = 24
For the letter b it is x = 20
16000000000000.
Hope it helped
D. Plug in the options to both equations and find which makes both true.
