C is the correct answer to your question
Answer:
7 minutes
Step-by-step explanation:
From the question :
Descent = ascent
Initial height * descent rate = initial position * ascent rate
Plane on ground is at an initial position or height of 0
42000 - 3300t = 0 + 2700t
Where, t = time
-3300t - 2700t = 0 - 42000
-6000t = - 42000
t = 42000 / 6000
t = 7 minutes
(Y+40)+(x+2y)=180
3y+x=140
2x+(y+20)=180
2x+y=160
Simultaneous equation
3y+x=140
Y+2x=160
Solve for y
Y=24
3(24)+x=140
X=140-72=68
not sure about the answer
The appropriate unit would be pounds/lbs.
