Answer:
d. x = 3, y = 4
Explanation:
Well in the following system of equations,

We need to single out x or y in either equations,
let's do the first one for x.
x - y = -1
+y to both sides
x = y - 1
Now we plug in y - 1 for x in x + 2y = 11
(y - 1) + 2y = 11
Combine like terms
3y - 1 = 11
+1
3y = 12
Divide 3 by both sides
y = 4
Now we plug in 4 for y in x - y = -1
x - 4 = -1
+4 to both sides
x = 3
(3,4)
Thus,
the answer is d. x = 3, y = 4.
Hope this helps :)