Identify the flowchart proof for the two-column proof.

Given: m∠PQR=90° and m∠b=5·m∠a
Prove: m∠a=15°
Two-Column Proof
1. m∠PQR=90°, m∠b=5·m∠a (Given)
2. m∠a+m∠b=m∠PQR (∠s Add. Post.)
3. m∠a+5·m∠a=90°(Subst. Prop. of = )
4. 6⋅m∠a=90° (Simplify.)
5. m∠a=15° (Div. Prop. of = )