Question 993929
x is the number of miles you can go on a tank of gas.


if you get 16 miles per gallon, then x = 21 * 16.


if you get 18 miles per gallon, than x = 21 * 18.


x has to be greater than or equal to 21 * 16.


x has to be less than or equal to 21 * 18.


if x is greater than or equal to 16 * 21, then 16 * 21 must be less  than or equal to x.


you can now write your inequality as 16 * 21 is less than or equal to x which is less than or equal to 18 * 21.


the symbol for less than or equal to is <=.


your inequality can therefore be expressed as 16 * 21 <= x <= 21 * 18.


simplify this further to get:


336 <= x <= 378


this says that the minimum number of miles you will travel on a tank of gas is 336 miles and the maximum number of miles you will travel on the same tank of gas is 378.