Answer:
7/15
Step-by-step explanation:
Well 4/5 - 1/3 = 12 / 15 - 5 / 15 which is equal to 7/15, but there aren't any expressions in your question.
42x can be factored into 7(6x), and 49 is square, meaning it can be factored into 7 squared. I believe the factored expression would be 7(6x + 7) because 7 is the greatest common factor between both numbers.
I have no clue I just need the points have a good day tho :)