Oooh I don't know the exact wording, but it is the property that states that the order of the numbers in the equation can be switched and still equal the same thing as long as the signs are still kept.
Answer:
A)
Step-by-step explanation:
To find the answer we must solve each of the systems separately. Starting with the first one:
x + y = 2
2x - y = 10
We must find what x or y is equal to and then replace it in the second equation. I'll go with y as it seems easier:
x + y = 2
y = 2 - x
Now that we found y we replace it in the second equation this way. Be careful with the signs, the minus with change our signs:
2x - (2 - x) = 10
2x - 2 + x = 10
3x = 12
x = 12/3
x = 4
Now that we have x, we replace the variable with its value in one of the equations. Again, for simplicity I'll go with the one that seems easier.
4 + y = 2
y = 2 - 4
y = - 2
