The point of intersection of the lines has an e-coordinate of?

Since you're only interested in x, you can use the first equation to write an expression for y that can be substituted into the second equation.
.. y = k -x
.. 2x +3(k -x) = k +1
.. -x +3k = k +1 . . . . . collect terms
.. 2k -1 -x = 0 . . . . . . subtract k+1
.. 2k -1 = x . . . . . . . . .add x

The 3rd selection is appropriate.

13. (a-b)^2=a^2-2ab+b^2
   B is the answer
14. B is the answer
     ( x+9)(x-3)= x^2+6x-27
15. B is the answer
    (x+6)(x-5)=x^2+x-30
16. D is the answer
  (x-6y)(x-4y)=x^2-10xy+24y^2
17. C is the answer
(2x+5)(3x-4)=6x^2+7x-20
18. B is the answer
(5x+7)(x-2)=5x^2-3x-14