I think this is a least common multiple question
So they would all arrive on day 504, (which probably is a few years)
8 = 2 × 2 × 2
18 = 2 × 3 × 3
21 = 3 × 7
I might be right I might be wrong, IM not positively sure but yknow
The answer is 10x+9y+6 if your trying to combine all like terms.
the slope is of the equation is 2/3
The correct answer is
d=50t
Where; d is the distance covered in miles
t is the time taken in hours