2. Solve:
у = 3х
x = -2y + 70

 (10,30)

Step-by-step explanation:

y = 3x  

x = -2y + 70  

Solve by using the substitution method. Substitute the value for x into the first equation and solve for y.

y = 3(-2y + 70)      Multiply it out

  y = -6y + 210            Add 6y to both sides

+6y    +6y

7y = 210

 y =  30  

Since y is equal to 30, input the value for y into the equation and solve for x.

30 = 3x    Divide both sides by 3

x = 10

if this is really you s much. i only have 3 points left and i have 2 questions to ask

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.