Anybody Know This. ?

Let the closed interval [a , b] be the domain of function f. the domain of f(x - 3) is given by (a) the open interval (a , b) (b) the closed interval [a , b] (c) the closed interval [a - 3 , b - 3] (d) the closed interval [a + 3 , b + 3]

Simplify the given expression leaving the answer in improper fraction form. 2/3+5/6

6. sarah saved $12.75 every week for a number of weeks, w. she received an additional $25 during the last week in which she saved money. write and solve an equation to find the number of weeks, w, for which sarah had saved money if she has $114.25 now.