Since a and 5 aren't like terms, you would write the expression as 
-15 < 3n < 6
Divide all sides by 3
-5 < n < 2
Now you need all integers between -5 and 2.
-4, -3, -2, -1, 0, 1
for converting km to meters
1 km = 1000 m
5807 km = 1000 × 5807 m
= 5807000m ...
for converting cups to gallons
1 cup = 0.0625 gallons
2144 cups = 0.0625 × 2144 gallons
= 134 gallons
In order to determine the correct answer, it would be helpful to set up equations. We do as follows:
Let x = students
y = adults
x + y = 215
.50x + 2y = 250
SOlving simultaneously, we have:
x = 120 students
y = 95 adults
Hope this answers the question. Have a nice day.
