2x+5/3=8 solve this equation

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

Jack has a piece of red ribbon that is two times as long as his piece of blue ribbon. he says that he can use two different equation to find out how long his piece of red ribbon is compared to his piece of blue ribbon is. is he correct? explain his reasoning

Pranza plotted point a in the coordinate plane below.