Please answer these questions and explain to me the way to learn and solve them I need to understand the concept and the correct answer for each question I have exam next week and I have to learn them so well .write in large alphabet and please write clearly I'm not a English speaker . Thanks

In Exercises 15 - 18, use the following information to eval- uate the given limit, when possible. If it is not possible to determine the limit, state why not. lim f(x) = 2, lim f(x) = 1, f(1) = 1/5 x- 1 x-+ 10 . lim g(x) = 0, lim g(x) = 7, 9(10) = 1 x-+1 x-10 15. lim f(x) 9(x) x-+1 16. lim cos (g(x)) x->10 17. lim f(x)g(x) X-+1 18. lim g (5f(x) ) x - 1