Explanation:
Formula to calculate pH of a chemical or solution is as follows.
pH =
Therefore, calculate the pH of given chemicals as follows.
1). Oven cleaner
pH =
=
= 13
2). Water
pH =
=
= 6.15
3). Blood
pH =
=
= 7.40
4). Vinegar
pH =
=
= 2.20
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:
We have been given that Sterre charges $35 to file tax returns, but files for free if she only needs the easiest form. Also, she donates $2 to clean water projects per tax return she files.
Further we know that Sterre charged $7,245 and made a donation of $1,242 this year for the tax returns she filed.
Let x be the number of free income tax returns and y be the number of $35 income tax returns.
Therefore, we can set up:
Since she donates $2 for each return that she files, therefore, we can set up:
Therefore,
Sterre filed 414 tax returns for free and filed 207 tax returns for $35.