SOLUTION: find the value of two numbers if their sum is 12 and their difference is 4

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Question 923083: find the value of two numbers if their sum is 12 and their difference is 4
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

let's two numbers be x and y
if their sum is 12, we have
x%2By=12....eq.1
and their difference is 4
x-y=4....eq.2
solve the system:
x%2By=12....eq.1
x-y=4....eq.2
_____________________add both
x%2Bcross%28y%29%2Bx-cross%28y%29=12%2B4
2x=16
x=16%2F2
highlight%28x=8%29
go to x%2By=12....eq.1 plug in x
8%2By=12
y=12-8
highlight%28y=4%29