I'm new to this forum. At the moment i'm trying to learn Primitive Root and also bit weak in my maths. I would appreciate if I could get a step by step explanation
for the following questions:

Question 1
Find the primitive root Z*19 (Z is integer). Refer to the attached image, i'm unable to insert Z symbol. The answer is 2,3,10,13,14,15.
Primitive Roots-question1.png

I have seen some video related to primitive roots they start by finding the Totient. So in this question to start of, do I need to find the Totient of 19?
I know its 18, but how do i get 2,3,10,13,14,15.

Question 2
Find x such that Ord43(X)=7