Question

1) |3k + 4| = 8?
2) |3x + 8| = 19?
3) |7x + 1| < 13?
4) |3k + 4| = 8?
5) |7x + 1| < 13?

Answer 1

There you have the first equality, you can solve the other two by using the very same method.
Regarding the inequalities, you will have to make a graph and find the solutions.

Answer 2

I will solve the first for you, you should be able to do the rest (they are all done the same way)\[\left| 3k+4 \right|=19\]means that either

3k+4=19 or 3k+4=-19
3k=15 or 3k=-23
k=5 or k=-23/3
so k={-23/3,5}

Answer 3

If |x| = +x if x >0
= -x if x < 0