<h2>
Answer:</h2>
The area of the top surface of the washer is: 160.14 square mm.
<h2>
Step-by-step explanation:</h2>
The top of the surface is in the shape of a annulus with a outer radius of 10 mm and a inner radius of 7 mm ( since the diameter of the hole is: 14 mm and we know that the radius is half of the diameter)
Now, we know that the area of the annulus region is given by:

where R is the outer radius and r is the inner radius.
Here we have:

Hence, we have:

You can round 976 to 1000 and 522 to 500. So it would be
1000 - 500 = 500. The answer you would get after subtracting 976-522 would be more than 400 if you round it.
We are given equation g = 748u, where g is the total number of gallons of water used and u is the number of units.
We can see that the number of units of water being used by customers.
The number of units of water doesn't depend on the total number of gallons of water used.
Therefore, the number of units u is an independent variable.
The value of the total number of gallons is totally depends on the number of units used.
Therefore, the total number of gallons of water used g is a dependent variable.
So, we can conclude following statements:
1) g is the dependent variable.
2) u is the independent variable.
Answer:
When we do a scale model of something (like a building, a house, or whatever) al the properties of the original thing must also be in the model.
So for example, you want to do a model of a house, and in the backyard of the house there are 4 trees, then in the model of the house you also need to put 4 trees in the backyard (indifferent of the scale of the model).
Then the number of boulders in the really fountain should be the same as the number of boulders in the scale model of the fountain.