The lowest elevation in louisiana is 8 feet below sea level. the highest elevation is 535 feet above sea level. what is the difference in elevation between the highest and lowest points.

You can usually translate below to mean the number is minus or at least smaller than something else. In this case it is minus. So the answer is found as

535 - - 8 = 543 feet. The first minus sign means difference and the second means below sea level. (535 is feet above sea level). This is one of those cases where it makes sense to say that a minus times a minus is a plus.

Let's try this a slightly different way. Suppose there is a hill above a gully. The hill is 30 feet above the gully. The gully has a bottom that is 8 feet below where the hill begins. If you wanted to walk from the top of the hill to the bottom of the gully, how far would you have to go? Never mind all the plus and minus stuff. Just draw the picture, and see what happens. Or imagine you are doing the walking.

Wouldn't you have to go 30 + 8 feet? Isnt' that 38 feet? Same with your Louisiana problem. It (the Louisiana problem) is just more mathematical. And getting two minus signs to equal a plus is no easy trick.

Be sure you understand the answer to this problem. It is one of the cornerstone's of Algebra.

let y equal to

the total fare and x is the mile of taxi ride. so the equation is

y = 0.55x + 1.75

since susie has

$10 to spend for a taxi cab, so he can have

10 = 0.55x +

1.75

x = 15 miles of

taxi ride

so the system of

inequality is

10 < 0.55x +

1.75

x > 2