Its not 70 its 56, because you have to see how many minutes it takes for 1 to do 4 walls which would be 40*8.
Then you have to see if how many minutes its take a person to do one wall which is 8*40/4 from getting the amount of the 1 person doing 4 walls and get 80.
Then you need to see how many walls a person can paint 7 walls out of 10 people.So, we know how many minutes for each wall which is 80 and then multiply it by 7 to get 560 and divide it by 10 to get a product of 56.
The expression:

gives the distance traveled by the aircraft in t hours, so, for t = 6:
Answer:

Step-by-step explanation:
let the number be n , then
4 - 4n = 2n ( add 4n to both sides )
4 = 6n ( divide both sides by 6 )
= n
The number is 