It took them 4 days to install 480 chairs which means if they were working at a constant rate they got 120 chairs installed daily. with 360 chairs left that means in 3 days they will finish. so overall, it took the workers 7 days to finish, or a week.
The given expression is:

So, there are two terms in the expression
1)

2) -5
The constant term is -5.
The co-efficient of

is 4.
3.7kg is also equal to 3700 grams
3700+620 grams
= 4320 grams
= 4320/1000 kg
= 4.32 kg
That's 6! (factorial). It's 720.