Iget confused with synthetic division

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

When i add money am i supposed to make it like this 7+12 or 7.00+12.00 because i got 19 dollars for my answer

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%