Solve the following system of equations using elimination:
-x+5y=8
And
3x+7y=-2

x=-3, y=1. (-3, 1).

Step-by-step explanation:

-x+5y=8

3x+7y=-2

3(-x+5y)=3(8)

3x+7y=-2

-3x+15y=24

3x+7y=-2

22y=22

y=22/22

y=1

-x+5(1)=8

-x+5=8

-x=8-5

-x=3

x=-3

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.

good luck on your studies! : )

david edward.