6 people go in each car because since there is only six seats 6x1 equal 6 and there i no remainder
That is not correct. I will help you. Begin by subtracting the 9x from both sides, like this: 9x - 9x + 2y = 6 - 9x. That simplifies to 2y = -9x + 6. Now divide both sides by 2 to get y all alone, like this:

. That reduces down to

. That is slope-intercept form. y = mx + b.
50/2.5=
20
Unit rate is 20 miles per gallon
2π radians is equal to 360° which is just π rad/180° so:
120°(π/180°)=2π/3