Answer:
The answer is 46.
Step-by-step explanation:
You have to substitute the value of a and c into the expression :

Let a = 10,
Let c = 4,



5x-2x+6x+40-9+1-x+3x-8+15+7
First you would combine like terms:
5x - 2x + 6x - x + 3x = 11x and
40 - 9 + 1 - 8 + 15 + 7 = 46, so the simplified expression would be
11x + 46
This question is solved applying the formula of the area of the rectangle, and finding it's width. To do this, we solve a quadratic equation, and we get that the cardboard has a width of 1.5 feet.
Area of a rectangle:
The area of rectangle of length l and width w is given by:

w(2w + 3) = 9
From this, we get that:

Solving a quadratic equation:
Given a second order polynomial expressed by the following equation:
.
This polynomial has roots
such that
, given by the following formulas:
In this question:


Thus a quadratic equation with 
Then


Width is a positive measure, thus, the width of the cardboard is of 1.5 feet.
Another similar problem can be found at brainly.com/question/16995958
Answer: -300 meters
Step-by-step explanation: If he started from 0 (sea level) and went 300 meters under, meaning 0-300=-300 meters.