so 5 people work each one for 21 minutes, that means 21+21+21+21+21 minutes altogether, namely 105 minutes, it took that long for 7 walls, hmmmm how long for just one wall then? well, 105 ÷ 7, namely 15 minutes then, for just 1 wall.
now, if it takes 15 minutes of work to do one wall, what about 5 walls? well, that'd be 15*5 or 75 minutes.
so if we have 3 folks working, how much would each one work? well, 75 ÷ 3, namely 25 minutes, so each of them will work 25 minutes, namely 25+25+25 minutes, so in 25 minutes, they'll be done with 5 walls.
18 + (-8) + 11
Adding a negative number is the same as subtracting a positive number. So "18-8" is the same thing as "18+ -8".
18 - 8 + 11
10 + 11
21
Divide 5.60 by 70 and that's the price per ounce
(a) Truck carries 90 gallons of diesel fuel to 660 miles.
So, 1 gallon of diesel fuel to 660/90 = 22/3 miles.
30 gallons of diesel fuel to = 220 miles.
Hence, if x-axis represents the number of miles and y-axis represents the number of gallons, then, (660, 90) and (220, 30) are points on the graph.
Join (660, 90) and (220, 30), we get the graph of a line.
Note that (0, 0) is also a point on the line.
Equation of the line is .
(b) x represents the number of miles. Therefore, the possible values for x is the closed interval [0, 660].
Hence, the domain of the function is [0, 660].
(c) Origin represents that the truck is not moving and there is no diesel fuel loaded in the truck.