Answer:

Step-by-step explanation:
The systems of equations are
Let us assume the rate of the current be c
Now actual speed against the current is (15 - c)
And, the actual speed with the current is (15 + c)
Here we applied the time formula i.e. distance by speed
Also the upstream time - downstream time = 4
Now the equations are

Answer:
Soil bacteria convert nitrogen gas into ammonia, nitrites, and then nitrates. Nitrates are then absorbed by producers.
Step-by-step explanation:
.
Answer:
0.416 au
Step-by-step explanation:
Let y1=8sin(x) and y2=8cos(x), we must find the area between y1 and y2

The common minimum of those three numbers is 120.
1 gallon = 2.93
2 gallons = 5.86
3 gallons = 8.86
Therefore the correct table is D.