Please help me out i need some assistance

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]

Solve with work adding cheese to a mcdonalds quarter pounder increases the fat content from 21g to 30g. what is the percent of change ?

Complete the solution of the equation. find the value of y when x equals to 6 4x+y=20