Proof: Complementary Angles

Let's prove the following theorem:

if ∠AXB and ∠BXC are complementary and ∠BXC and ∠CXD are complementary, then m∠AXB = m∠CXD

A B C D X

Proof:

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Given
1 AXB and ∠BXC are complementary
2 BXC and ∠CXD are complementary
Proof Table
# Claim Reason
1 (m∠AXB) + (m∠BXC) = 90 if ∠AXB and ∠BXC are complementary, then (m∠AXB) + (m∠BXC) = 90
2 (m∠BXC) + (m∠CXD) = 90 if ∠BXC and ∠CXD are complementary, then (m∠BXC) + (m∠CXD) = 90
3 m∠AXB = 90 + ((m∠BXC) ⋅ (-1)) if (m∠AXB) + (m∠BXC) = 90, then m∠AXB = 90 + ((m∠BXC) ⋅ (-1))
4 m∠CXD = 90 + ((m∠BXC) ⋅ (-1)) if (m∠BXC) + (m∠CXD) = 90, then m∠CXD = 90 + ((m∠BXC) ⋅ (-1))
5 m∠AXB = m∠CXD if m∠AXB = 90 + ((m∠BXC) ⋅ (-1)) and m∠CXD = 90 + ((m∠BXC) ⋅ (-1)), then m∠AXB = m∠CXD
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