a.)

Consider the augmented matrix:

Matrix A := [[1, -1/3, -1],[2/3, -1/4, -1]]

Multiply -2/3 times row 1 (R_1) and add to R_2.

Thus, we have: [[1, -1/3, -1],[0, -1/36, -1/3]]

Multiply R_2 by -12 and add to R_1.

[[1, 0, 3],[0, -1/36, -1/3]]

Divide R_2 by -1/36

[[1, 0, 3],[0, 1, 12]]

Thus, we have reduced echelon form, where x_ 1 = 3 and x_2 = 12 (or in your case, x and y, respectively).

I'll let you check to see that it works.

b.) Try it- if you get stuck show what you attempted and we can probably show where you went wrong.