-18 = z -7 plz help me with this equation

Which is the graph of the linear equation x – 2y = 6?

Adan has decided to purchase an $9000 car. he plans on putting 20% down toward the purchase and financing the rest at 7.9% interest rate for 3 years. find his monthly payment a) $225.29 b) $298.81 c) $204.78 d) $236.89

How would you describe the difference between the graphs of f(x) = 2x2 and g(x) = -2x2?