SOLUTION: Solve the system by substitution. x + y = 12 y = 2x Solve the system by addition. 5x � 3y = 13 4x � 3y = 11

Question 90768: Solve the system by substitution.
x + y = 12
y = 2x

Solve the system by addition.
5x � 3y = 13
4x � 3y = 11

Answer by malakumar_kos@yahoo.com(315) (Show Source): You can put this solution on YOUR website!

Solve the system by substitution.
x + y = 12
y = 2x
Solve the system by addition.
5x � 3y = 13
4x � 3y = 11

1) x+y = 12.....(1)
y = 2x.......(2)
substitute for y in (1)
x+2x = 12
3x = 12 or x = 12/3 = 4
y = 2*4 = 8
The required solution is x = 4 and y = 8

2)5x-3y =13.....(1)
4x-3y = 11.....(2)
multiply (2) by -1 and add to (1)
5x-3y = 13
-4x+3y = -11
we get x = 2 because -3y & 3y gets cancelled
substitute for x in (1)
5*2-3y = 13
10-13 = 3y
3y = -3 or y = -1
The solution is x = 2 and y = -1
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