this is algebra 1 i need help anybody understand?

Answer:
x=3 and y=4
Step-by-step explanation:
solve x-y=-1 to get x:
x−y=−1
x−y+y=−1+y(Add y to both sides)
x=y−1
Substitute y−1 for the x value in x+2y=11:
3y/3=12/3
y=4
Substitute 4 for the y value in x=y−1:
x=y−1
x=4−1
x=3
so y=4, and x=3
Answer:
d. x = 3, y = 4
Step-by-step explanation:
Well in the following system of equations,
[tex]\left \{ {{x-y=-1} \atop {x+2y= 11}} \right.[/tex]
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 :)