Which sketch constraint locks the endpoint of a line to the endpoint of another line in Onshape?

Aseries piping system conveys methyl alcohol. the system consists of 70 m of 1- nominal pipe follow by 50 m of 2-nominal pipe, both schedule 40 commercial steel. the 1-nominal pipe contains 3 90° elbows (regular) anda fully open gate valve, all threaded. the pressure drop through the system is 150 kpa. determine the volume flow rate through the system that is horizontally laid.