Solve for y by setting one equation =to X after that you can substitute the equation into the other one let's set the first one in X= FORM
X-7y=10
-2x+14y=-20
Add 7y to both sides of the first equation to let x stand alone
X=7y+10
Now you can substitute x on the second equation
-2 (7y+10)+14y=-20
Distribute
-14y-20+14y=-20
Add and simplify
Us cancel out =0
-20=-20
0=0
They are the same equations you can also divide the second equation by -2 which would make it look like this
X-7y=10
-2 (x-7y=10)
Let me know if I have answered your question
1. The function

is a parabola of the form

. The the formula for the axis of symmetry of a parabola is

. We can infer from our function that

and

, so lets replace those values in our formula:





We can conclude that to the left of the line of symmetry the ball is reaching its maximum height, and to the right of the line of symmetry the ball is falling.
2. Lets check how much time the ball takes to reach its maximum height and return to the ground. To do that we are going to set the height equal to zero:



or


or

From our previous point we know that the ball reaches its maximum time at

, which means that <span>
it takes 1.5 seconds to reach the maximum height and 1.5 seconds to fall back to the ground.</span>