=SUM(IF(Jour1Train=A5,Jour1Abord),IF(Jour2Train=A5,Jour2Abord),IF(Jour3Train=A5,Jour3Abord),IF(Jour4Train=A5,Jour4Abord),IF(Jour5Train=A5,Jour5Abord),,IF(Jour6Train=A5,Jour6Abord))
how to leave the cells that are not used empty blank instead of 0