Find a constant variation for each direct variation then find the value of y when x= 3/4. y=2/3 when x=1/4

I'll give brainliest if you answer right : )

What is the definition of exponential decay?

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