The amount of paint that david needs to cover a cube is directly proportional to the surface area. if david can completely cover a cube of side length 2 feet with exactly 16 quarts of paint, how big a cube (in terms of edge length in feet) can david cover with 169 quarts of paint?

The cube must be 21.125 feet long.

Step-by-step explanation:

David can completely cover a cube of side length equal to 2 feet, using 16 quarts of paint.

With this we make a conversion factor:

feet/quarts = 0.125 feet/quarts

This means that with each quart of paint you can paint a 0.125-foot long cube

We need to know how big is the length of a cube that can be covered with 169 quarts of paint

Then we use the conversion factor found earlier

The cube must be 21.125 feet long.

b. astronomers

option 3 . (5x + 1) - (-10x + 6)

step-by-step explanation:

option 1 :

(4x + 3) + (-9x + 4)

or 4x+3 -9x + 4

or -5x + 7

option 2

(x - 2) - (6x - 9)

or x-2-6x + 9

or -5x + 7

option 3

(5x+ + 6)

or 5x + 1 + 10x -6

or 15x -5

option 4

-4x+2x+7-3x

-7x + 2x + 7

-5x + 7

hence only option 3 did   not satisfy the given simplify expression.