Answer:
x = (5+a)/2
y = (5-a)/2
Step-by-step explanation:
x+y=5
x−y=a
Add the two equations together
x+y=5
x−y=a
-----------------
2x = 5+a
Divide each side by 2
2x/2 = (5+a)/2
x = (5+a)/2
Multiply the second equation by -1 -x+y = -a
Then add the two equations together
x+y=5
-x+y=-a
-------------------
2y = 5-a
Divide each equation by 2
2y/2 = (5-a)/2
y = (5-a)/2
