Which lines are parallel? justify your answer

What does x = in this equation x+3+2x=x+5

Kelli swam upstream for some distance in a hour.she then swam downstream the same river for the same distance in only 6 minutes.if the river flows at 5km/hr, how fast can kelli swim in still water?

Three runners competed in a race data were collected at each mile mark for each runner if the runner ran at a constant pace the data would be linear