In the figure a||b, and both lines are intersected by transversal t. complete the statements to prove that m∠1 = m∠5.

(given)
m∠1 + m∠3 = 180° (linear pair theorem)
m∠5 + m∠6 = 180° (linear pair theorem)
m∠1 + m∠3 = ∠5 + ∠6 ()
m∠3 = m∠6 ()
m∠1 = m∠5 (subtraction property of equality)