Using a system of equation, we have that:
a)
- x, which is the cost of on-site service.
- y, which is the cost of at-store service.
- z, which is the cost of by-mail service.
b)
The system is:



c)
The cost of one on-site repair service is of $90.
Item a:
The variables are:
- x, which is the cost of on-site service.
- y, which is the cost of at-store service.
- z, which is the cost of by-mail service.
Item b:
On-site service costs <u>3 times as much as at-store service</u>, thus:

By mail service costs <u>$10 less than at-store</u> service, thus:

Last week, the shop completed <u>15 services on-site, 40 services at-store, and 5 services by mail for total sales of $3100</u>, thus:

The system is:



Item c:
- The cost of one on-site repair service is x.
- First, replacing the first two equations into the third, we find y, and then with it we find x.






Then

The cost of one on-site repair service is of $90.
A similar problem is given at brainly.com/question/24823220
About 16 copies cost the same amounts
Answer:

Step-by-step explanation:
Let assume that Earth is a sphere, the following trigonometric diagram is constructed and presented below. The central angle is given by this inverse trigonometric equation:



The distance of the portion of Earth that can be seen is:


Answer:
to be fair this looks hard but i can do just give me five mins
Step-by-step explanation:
No, a closed circle does include that number.
Closed circles are used for greater than or equal to or less than or equal to
Open circles are only used for greater than or less than