Question

Given: p || q, and r || s (figure).

Prove: ∠1 and ∠14 are supplementary angles.
Diagram: http://imgur.com/REM6Dq5
http://imgur.com/0YTvyWD

Answer 1

You can prove it because if p and q are parallel and r and s also are parallel then angle 1 and angle 14 would both be right angles (90 degrees)
Supplementary means they add up to 180 degrees, so that's why 1 and 14 are supplementary

I hope this helps