Your question is a bit unclear, but I will try to answer it anyway.
The expression 3x + 2(x - 1) - 4 simplified is:
3x + 2(x - 1) - 4
= 3x + 2x - 2 - 4
= 5x - 6
I cannot tell what the answers are but I am guessing they are these?:
A) 3x + 2x - 2 - 4
B) 5x - 6
C) 3(x - 4)
D) 3(x + 2) - 6
E) 6(x - 1)
Answer A is one, and so is answer B. If I read your question accurately.
I hope I helped!
The common denominator of these fractions will be 12. So Ann worked 306/12 hours, Mary worked 244/12 hours, and John worked 123 hours, meaning they have worked 673/12 hours together.