What do you need to do first before using substitution?

Solve for one of the variables first ,, then whatever answer you receive from x or y , you then begin to plug it in to get other variable.

The  pan-african movement  was an "emotional, cultural, psychological and ideological  movement  that began among the  african  dispora in the western hemisphere, for a closer  purpose, so that  african  people could feel secure, attain political, economic as well as psychological power visa vis other races or world regions" .