Answer:
Step-by-step explanation:
Given that a large mixing tank initially holds 400 gallons of water in which 70 pounds of salt have been dissolved. Pure water is pumped into the tank at a rate of 4 gal/min, and when the solution is well stirred, it is then pumped out at the same rate.
Let Q(t) be the quantity of salt at time t.
Q(0) = 70 pounds
Inflow of water = outflow = 4 gal/min
So resulting volume of tank at time t = 400 gallons
Rate of change of salt = inflow - outflow
= 0 - 
i.e. 
This is a variable separable equation

Use when t =0 Q = 70
A =70
So A(t) = Q(t) =
and
A(0) = Q(0) = 70 lbs.
Triangle b because it only has 3 sides
(7x - 23)° + (11x + 23)° = 180°
7x - 23° + 11x + 23° = 180°
18x = 180° / : 18
x = 10°
-72-4x^2+8x^3-36x/x-3
-4(18+x^2-2x^3+9x)/x-3
-4(-2x^3+x^2+9x+18)/x-3
-4(-2x^2x(x-3)-5x x(x-3)-6(x-3) )/x-3
-4 x(-(x-3) ) x (2x^2+5x+6)/x-3
-4 x (-1) x (2x^2 +5x+6)
8x^2+20x+24