Answer:
the answer is -3x² caused when -x divide with 3x it will became -3x²
let the speed of plane in still air be x and that wind be y
therefore:
x+y=490
x-y=390
next we solve for the values of x and y, first we add the above equations. This will give us:
2x=880
x=880/2
x=440 miles per hour.
substituting the value of x in one of the equations and solving for y we get:
440+y=490
y=490-440
y=50 miles per hour
The <em>total surface</em> area of the three figures are 702 square feet.
<h3>How to estimate the amount of metal needed to produce a given amount of figures</h3>
According to this problem, we are required to determine the amount of metal needed to build three pieces with the dimensions presented in the figure.
In this case, we need to estimate the <em>total</em> surface area (
), in square feet, required for the production of the three pieces, that is, the product of the number of pieces (<em>n</em>), no unit, and the surface area of each piece (<em>A</em>).
Now we proceed to calculate the total surface area:


![+(5\,ft)\cdot (8\,ft)+2\cdot (3\,ft)\cdot (5\,ft) + 2\cdot (4\,ft)\cdot (2\,ft) + (3\,ft)\cdot (4\,ft) ]](https://tex.z-dn.net/?f=%2B%285%5C%2Cft%29%5Ccdot%20%288%5C%2Cft%29%2B2%5Ccdot%20%283%5C%2Cft%29%5Ccdot%20%285%5C%2Cft%29%20%2B%202%5Ccdot%20%284%5C%2Cft%29%5Ccdot%20%282%5C%2Cft%29%20%2B%20%283%5C%2Cft%29%5Ccdot%20%284%5C%2Cft%29%20%5D)

The <em>total surface</em> area of the three figures are 702 square feet. 
To learn more on surface areas, we kindly invite to check this verified question: brainly.com/question/2835293
Answer:
48.5 us cups
Step-by-step explanation:
D) its hard to keep something a secret, seems like the most accurate answer for this question.