SOLUTION: the sum of two numbers is 80 and their difference is half their addition. find the numbers.

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Question 905849: the sum of two numbers is 80 and their difference is half their addition. find the numbers.
Found 2 solutions by 100601, MathLover1:
Answer by 100601(6) About Me  (Show Source):
You can put this solution on YOUR website!
Substitute the numbers for x and y. This will be a system of equations, which means that there will be two or more equations.
x= one of the numbers
y= one of the numbers
x+y= 80
x-y=1/2(x+y)
Substitute x+y for 80.
x-y=1/2(80)
x-y=40
Now that you've simplified the equation, here are the two equations:
x+y=80
x-y=40
You can subtract the two equations from each other:
(x+y=80)
- (x-y=40)
----------
2y=40
y=20
Because y=20, x=60 since y+x=80.

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

given:
the sum of two numbers, x and y, is 80:
x%2By=80 ..............eq.1
and their difference is half their addition:
x-y=80%2F2
x-y=40.............eq.2
solve the system:
x%2By=80 ..............eq.1
x-y=40.............eq.2
_______________________________add both
x%2By%2Bx-y=80%2B40
2x%2Bcross%28y%29-cross%28y%29=120
2x=120
x=120%2F2
highlight%28x=60%29
find y
y=80-x
y=80-60
highlight%28y=20%29