A. All the equations are in slope intercept form, so all that's needed to do is plug in 2/3 as the x value in each equation and if the result is 4, then you got the answer.
Convert 322 kilometers to meters and that's your answer.
Answer:
First, let's move all terms to one side,

When given this form (ax^2+bx+c=0), there will be two solutions at the end.
1) 
2) 
where, a=1, b=-8, c=6

Simplify,

Simplify,

Hope it helps!
1 ft = 12 inches. 6.5 ft = 78 inches.
I hope this helps!