Question 469698
Solve each system by elimination.
Just add the two equations, this will eliminate y, leaving x
x - y = 11
2x+ y = 19
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3x + 0 = 30
3x = 30
divide both sides by 3
1x = {{{30/3}}} 
x = 10
:
Use the 2nd equation to find y
2x + y = 19
Replace x with 10
2(10) + y = 19
20 + y = 19
subtract 20 from each side
y = 19 - 20
y = -1
:
The solutions: x = 10, y = -1
:
:
Check this using the 1st equation
x - y = 11
Replace x with 10 and y with -1, see if it is true
10 - (-1) = 11
minus a minus is a plus, therefore
10 + 1 = 11; confirms our solution