55mph.
you can solve it using the equation distance=speed x time
your total distance is 714, and you have 2 trains, one traveling some speed, x, and one traveling x+8, both traveling for 7 hours.
your equation would look like this

and you can then solve for x, which would be 47. this is the speed of the slower train, but 47+8=55 with give you the speed of the faster train.
Answer:
See explanation
Step-by-step explanation:
Given 
According to the order of the vertices,
- side AB in triangle ABC (the first and the second vertices) is congruent to side AD in triangle ADC (the first and the second vertices);
- side BC in triangle ABC (the second and the third vertices) is congruent to side DC in triangle ADC (the second and the third vertices);
- side AC in triangle ABC (the first and the third vertices) is congruent to side AC in triangle ADC (the first and the third vertices);
- angle BAC in triangle ABC is congruent to angle DAC in triangle ADC (the first vertex in each triangle is in the middle when naming the angles);
- angle ABC in triangle ABC is congruent to angle ADC in triangle ADC (the second vertex in each triangle is in the middle when naming the angles);
- angle BCA in triangle ABC is congruent to angle DCA in triangle ADC (the third vertex in each triangle is in the middle when naming the angles);
I don't think those two expressions would even be equal unless w = 0. You can't just add in a 2 from nowhere.
No because 4 square equals 2 square and since 3 isn't a perfect number, it would be 2 square times 3 square, which equals 6 square.
Subtract 3x from both sides:
-6y = -3x + 6
divide both sides by -6 to get y by itself:
y = 1/2x - 1
function notation is rewriting y as a function:
f(x) = 1/2x -1