A printing service charges a set-up fee of $12.50 for each order and 7 cents more for each copy. The total cost, C (in dollars), for an order of x copies is given
by the following.
C =0.07x+12.50
What is the total cost for an order of 20 copies?
___ dollars

the total cost for an order of 20 copies is $13.9

Step-by-step explanation:

Let x represent the number of copies ordered.

The printing service charges a set-up fee of $12.50 for each order and 7 cents more for each copy.

The equation representing the total cost, C (in dollars), for an order of x copies is expressed as

C = 0.07x + 12.50

Therefore, the total cost for an order of 20 copies would be

C = 0.07 × 20 + 12.5

C = 1.4 + 12.5

C = 13.9 dollars

step-by-step explanation:

12: 00 p.m. to 7: 00 p.m. is a total of 7 hours.

4: 00 p.m. to 7: 00 p.m. is a total of 3 hours.

this means that from 4: 00 p.m to 7: 00 p.m. this represents 3/7 of what was lost from 12: 00 p.m. to 7: 00 p.m.

after knowing this, after doing 11,600 - 6,800 = 4,800

4,800 represents 3/7 of what was lost for 7 hours.

we then divide 4,800 by 3 which gets 1,600.

because we know that 1,600 represents 1/7 of how much water was lost, we just have to multiply by 7, which gets 11,200.   after adding 11,200 to how much water was left at 7: 00 p.m. which was 6,800. 11,200 + 6,800 = 18,000

this means that the pool originally had 18,000 gallons in the pool.

you can also check your work by doing 18,000 - 4(1600), which becomes           1800 - 6400 which gets you 11,600.