Homer is 30 feet below sea level and Marge is 45 feet above sea level. Bart’s elevation is at the exact midpoint of those two values. What is the expression that model this problem, and which is Bart’s elevation?

7.5 m above sea level

We are given:

The elevation of Homer = -30 feet                         [30 feet below sea level]

The elevation of Marge = +45 feet                         [45 feet above sea level]

The elevation of Bart is at the exact mid-point of the elevations of Homer and Marge

The elevation of Bart:

We are given that the elevation of Bart is at the exact mid-point of the elevations of Homer and Marge

So, Half the distance between the elevation of Homer and Marge is the elevation of Bart

Elevation of Bart (with respect to the elevation of Homer) =

(elevation of Marge - Elevation of Homer) / 2

replacing the variables with the suitable values:

(+45 - (-30))/2

(45 + 30) / 2

75 / 2

Elevation of Bart (w.r.t. Homer) = 37.5 feet

Since this is the elevation of Bart with respect to Homer, we can say that Bart is 37.5 m above Homer

So, we can say that:

Elevation of Bart (w.r.t Homer) = Elevation of Bart - Elevation of Homer

replacing the values

37.5 = Elevation of Bart -(-30)

37.5 = Elevation of Bart + 30

Elevation of Bart = 7.5 m above sea level [subtracting 30 from both sides]

d, x=8

step-by-step explanation:

simplifying

4x + -5 = 2x + 11

reorder the terms:

-5 + 4x = 2x + 11

reorder the terms:

-5 + 4x = 11 + 2x

solving

-5 + 4x = 11 + 2x

solving for variable 'x'.

move all terms containing x to the left, all other terms to the right.

add '-2x' to each side of the equation.

-5 + 4x + -2x = 11 + 2x + -2x

combine like terms: 4x + -2x = 2x

-5 + 2x = 11 + 2x + -2x

combine like terms: 2x + -2x = 0

-5 + 2x = 11 + 0

-5 + 2x = 11

add '5' to each side of the equation.

-5 + 5 + 2x = 11 + 5

combine like terms: -5 + 5 = 0

0 + 2x = 11 + 5

2x = 11 + 5

combine like terms: 11 + 5 = 16

2x = 16

divide each side by '2'.