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bill k

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# Find value?

Please explain step by step how to mathematically prove the following:

x + y = 100

Find the value of x and y when x = y.

Obviously the answer is 50 but how do I get that answer mathematically?

### 4 Answers

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- KrishnamurthyLv 72 months ago
x + y = 100

When x = y

2y = 100

y = 50 and x = 50

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- Lisa ALv 72 months ago
YOu have two simultaneous equations in two variables/

x=y

x+y=100

So you can take the first equation, and substitute x for y into the second equation.

x + x = 100

2x = 100

x = 100/2

x = 50

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- iansandLv 72 months ago
Substitute x for y

x+x=100

2x=100

Halve both sides

x=50

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- Φ² = Φ+1Lv 72 months ago
x + y = 100

x + x = 100 as x = y

2x + 100

x = 100/2 = 50

and y = x = 50

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