What is the solution to the system of equations?

(5, 12)

Step-by-step explanation:

Start with:

3x + 2y = 39

5x -    y  = 13

We'll use elimination by addition/subtraction here.  Multiply the 2nd equation by 2 to obtain -2y, which cancels out the +2y in the first equation:

3x + 2y = 39

10x  -2y  = 26

13x          = 65

Dividing both sides by 13, we get x = 5.

Subbing 5 for x in the 2nd equation, we get 5(5) - y = 13.

Then 25 - y = 13, and      12 - y = 0.  Finally, y = 12.

The solution is (5, 12).

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.

ou would have 12 of each