We will put ur equation in y = mx + b form, and the slope will be in the m position.
14x + 7y = -9
7y = -14x - 9
y = (-14/7)x - 9/7
y = -2x - 9/7
y = mx + b
y = -2x + (-9/7)....as u can see, the -2 is in the m position and is therefore the slope.
He would travel 67 1/2 miles in an hour.
It equals 2 pounds hope this help buddy
Answer: Third option.
Please, see the detailed solution in the attache file.
Thanks