8times the quantity 4 decreased by w

If this is what I'm thinking then the answer would be
W-4(-8) or simplified when you combine like terms
W+32
The variable always goes in the front of the expression and -4 times -8 would give you positive 32. (Negative times negative always gives you a positive outcome)

She will need 5/8 bags for each square yard.

There is 240 red cars and there is 400 blue cars because 240/3=80 and 80*5=400