C=number of acres of corn
w=number of acres of wheat
total is 180 acres
c+w=180
wants to plant 3 times as many corn as wheat
c=3w
subsitute 3w for c in other
c+w=180
3w+w=180
4w=180
divide boh sides by 4
w=45
sub back
c=3w
c=3(45)
c=135
135 acres of corn and 45 acres of wheat
3 + 4 = 7 all marables in bag
The probability that the first marable is black

The probability that the second marable is black too

Together:
Answer:
dy/dt = - (1/5) ft/s = - 0.2 ft/s
Step-by-step explanation:
Given
L = 5 ft
Qin = 25 ft³/s
Qout = 30 ft³/s
h = 10 ft
dy/dt = ?
We can apply the relation
ΔQ = Qint - Qout = 25 ft³/s - 30 ft³/s
⇒ ΔQ = - 5 ft³/s
Then we use the formula
Q = v*A
where Q = ΔQ, A = L² is the area of square base and v = dy/dt is the rate of change in the depth of the solution in the tank
⇒ ΔQ = (dy/dt)*L²
⇒ dy/dt = ΔQ/L²
⇒ dy/dt = (- 5 ft³/s)/(5 ft)²
⇒ dy/dt = - (1/5) ft/s = - 0.2 ft/s