Proof: Add Number to Both Sides 5

Let's prove the following theorem:

if 9 + x = 14, then x = 5

Proof:

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Given
1 9 + x = 14
Proof Table
# Claim Reason
1 (-9) + (9 + x) = (-9) + 14 if 9 + x = 14, then (-9) + (9 + x) = (-9) + 14
2 (-9) + (9 + x) = x (-9) + (9 + x) = x
3 (-9) + 14 = 5 (-9) + 14 = 5
4 x = 5 if (-9) + 14 = 5 and (-9) + (9 + x) = x and (-9) + (9 + x) = (-9) + 14, then x = 5

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