This is a ratio and proportion problem.
A’s portion of work completed in 6 days.
B’s portion of work completed in 8 days.
Together A+B=1/6+1/8 =7/24 Find Lowest Common Denominator
That means they finish 7/24 ratio of work a day, so now we have to find how long it will take them.
Take 1 day, and divide it by 7/24 ratio of work
1/7/24=24/7=3.43 days to finish.