Spudery621 Spudery621
  • 16-08-2015
  • Mathematics
contestada

solve using the substitution method -7x+y =42 and 5x+13y =66

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pead
pead pead
  • 16-08-2015
-7x+y=42
y=42+7x 

5x+13y=66
Substitute for y (meaning put 42+7x into the equation above instead of y because they are equal - see second line of my answer above)

5x+13[42+7x]  = 66
5x +546 = 66
5x=66-546
5x=-480
x=-480/5
x=-96

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