7n-4=31
7n=31-4
7n=27
n=27/7
:n=3
It’s equation and it’s really easy to solve
Answer: Yes
Step-by-step explanation: 144 is a perfect square. In other words, it's possible to find a whole number that can be multiplied by itself that gives us 144.
In this case, we multiply 12 by 12 or 12² to get 144 which means 144 is a perfect square. Also, it's on our perfect square list which I will attach below.
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:
-2(5x-7)
Step-by-step explanation:
Factor until each factor is linear
I worked it out and I got south Africa