Answer:
D?
Step-by-step explanation:
24 pens divided by 2 boxes equals 12 pens per box.
5x+3y=58
5x-3y=22
(3y gets cancelled bc 3y-3y=0, then add 5x with 5x, so you're left with)
10x=80, (divide both sides by 10)
x=8
Now we look for y. So choose one formula from the two (let's say 5x + 3y=58)
Substitute x for 8 so it will look like---- 5(8)+3y=58
Multiply 5*8--- so you get -- 40+3y=58
Subtract 40 from both sides and you're left with 3y=18
divide both sides by 3
you get y=6
In conclusion, x=8 and y=6 hence, (8,6)
Answer:
Step-by-step explanation:
Amount of brine = 100 gal
amount of salt = 80 lb
rate of water running = 4 gal / min
Let A be the amount of salt in lb in the tank at any time t.
(a) dA/dt = rate of salt in - rate of salt out
Rate of salt in = 0
rate of salt out = A x 4 / 100 = A / 25 lb/min
So, dA/dt = 0 - A/25 = - A/25 lb/min



When t = 0, A = 80 lb
So,

(b) Now, A = 40 lb
So,


take log on both the sides

t = 17.3 minutes
Answer:
I would help you... But I think that you are supposed to have a picture and there is no picture.