Answer:3
Step-by-step explanation:
7x3=21 4x3=12 21÷12=9 3x3=9
Answer:
Step-by-step explanation:
This is a differential equation problem most easily solved with an exponential decay equation of the form
. We know that the initial amount of salt in the tank is 28 pounds, so
C = 28. Now we just need to find k.
The concentration of salt changes as the pure water flows in and the salt water flows out. So the change in concentration, where y is the concentration of salt in the tank, is
. Thus, the change in the concentration of salt is found in
inflow of salt - outflow of salt
Pure water, what is flowing into the tank, has no salt in it at all; and since we don't know how much salt is leaving (our unknown, basically), the outflow at 3 gal/min is 3 times the amount of salt leaving out of the 400 gallons of salt water at time t:

Therefore,
or just
and in terms of time,

Thus, our equation is
and filling in 16 for the number of minutes in t:
y = 24.834 pounds of salt
Divide total time by total miles:
<span>65 / 7 = 9.29 minutes per mile</span>
The bottom trapezoid is
(1/2) * h * (b2 + b1) =
(1/2)*11 * (31+25)
(1/2) * 11 * 56
308
The top parallelogram is
b * h = 12 * 14 = 168
308 +168 = 476 ft^2
Letter B
Answer:
7/5
Step-by-step explanation:
rewrite as an equation ..
3 4/5 \ x = 2 5/7
times x to both sides
2 5/7x= 3 4/5
divide 2 5/7 from both sides
x=7/5