Questions on Algebra: Expressions involving variables, substitution answered by real tutors!

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Question 154181: 2x+3y=21
-3x-6y=-24: 2x+3y=21
-3x-6y=-24
Answer by Alan3354(1187) About Me  (Show Source):
You can put this solution on YOUR website!
2x+3y=21 eqn 1
-3x-6y=-24 eqn 2
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4x+6y=42 eqn 1 doubled
Add
x + 0y = 18
x = 18
Sub for x in eqn 1
2*18 + 3y = 21
36 + 3y = 21
3y = -15
y = -5