Given: a || b; c || d
a) List all angles congruent to angle 3._____________________
b) If m∠ 2 = 53º, then m∠ 12 = ______ and m∠ 8 = ______.
c) m∠ 4 + m∠ 12 + m∠ 13 + m∠ 6 = _________.