The answer is A,
Because the constant in a problem does not change, therefore if 115x is changing 350 is the constant so it eliminates B, and they make 115 per hour but not the question so that eliminates D. but if the factory started with 115 pairs 115 would not be the variableit would be the constant, so that leaves A, they started with 350 pairs of shoes
Hope this helps!
d is the correct answer
x= 8 because 3x = 3 * 8, and 3*8 = 24