SOLUTION: i need you to help me with substitution, i dont get it

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Question 392848: i need you to help me with substitution, i dont get it
Answer by checkley79(3341) About Me  (Show Source):
You can put this solution on YOUR website!
x+y=15 or x=15-y
x*y=50
Now substitute (15-y) for x in the second equation & solve for y
(15-y)y=50
15y-y^2=50
y^2-15y+50=0
(x-10)(x-5)=0
x-10=0
x=10 ans.
10+y=15
y=15-10
y=5 ans.
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x-5=0
x=5 ans.
5+y=15
y=15-5
y=10 ans.