Hello, magentarita!
The cables of a suspension bridge are in the shape of a parabola.
The towers supporting the cable are 400 feet apart and 100 feet high.
If the cable is at a height of 10 feet midway between the towers,
what is the height of the cable at a point 50 feet from the center of the bridge? Place the parabola on a graph. Code:

(200,100)*  *(200,100)
:  :
:*  *:
: *  * :
: *  * :
: * :
: (0,10) :
:  :
  +    +    + 
200  200
The parabola opens upward and is symmetric to the yaxis.
. . Its general form is: .
Its yintercept is (0, 10) . . . Hence: .
It passes through (200, 100).
. . We have: .
Hence: .
When
Therefore, 50 feet from the center, the cable is feet high.