What is the constant of proportionality for y=3.99x

Which of these choices show a pair of equivalent expressions?

Will give brainliest what is the value of x? enter your answer in the box.

11. minitab software was used to find the lsrl for a study between x=age and y=days after arthroscopic shoulder surgery until an athlete could return to their sport. use the output to determine the prediction model and correlation between these two variables. predictor coef se coef t p constant -5.054 4.355 -1.16 0.279 age 0.2715 0.1427 1.9 0.094 r-sq = 31.16%