According to the system of equations above, what is the value of X ?

The correct answer is: 13

The given equations are,
             . . .(1)
         . . . (2)
From equation (1), we have


Using this value of y in equation (2), we get







The required value of x=13.
The correct option is C.

Note:
Here we find the value of y from equation (1) and use it in equation (2).
We could do it the other way and receive the same answer, that is, if we find the value of y from equation (2) and use it in equation (1) to find x, we get the same value of x as found in the solution above.
Students are encouraged to try this method too.