Answer:
Speed of plane in still air: 490 mile/hour
speed of wind: 70 mile/hour
Step-by-step explanation:
still speed = x wind speed = w
with wind: speed = still + wind
(x+w) * 3 = 1680 ...a
against wind: speed = still - wind
(x-w) * 4 = 1680 ...b
b-a ... 4x-4w-3x-3w = 0
x-7w = 0
x = 7w
substitution: (7w+w)*3 = 1680 8w = 560 wind speed (w) = 70
still speed (x) = 7w = 490 mile/hour
The complete question is
<span>Sarah rides her horse for 2 1/6 hrs with a constant speed of 6 km/hr and then for another 2 hours and 5 minutes with a constant speed of 12 km/hr what is her average speed for the total trip?</span>
we know that
speed=distance/time
1) Sarah rides her horse for 2 1/6 hrs with a constant speed of 6 km/hr
time=2 1/6 hrs----> 13/6 hrs
speed=6 km/h
distance=speed*time----> 6*(13/6)---> 13 km
2)for another 2 hours and 5 minutes with a constant speed of 12 km/hr
time=2hrs+5 minutes----> 2+(5/60)--> 125/60 hrs
speed=12 km/hrs
distance=speed*time----> 12*(125/60)---> 25 km
3) find the average speed for the total trip
total distance=13 km+25 km----> 38 km
total time=(13/6)+(125/60)----> (10*13+125)/60----> 4.25 hours
speed=38/4.25----> 8.94 km/hrs
the answer is
8.94 km/hrs
You can put it into expressions:
Your score would be x
Your friends score would be x +12
Hope This Helps You!
Good Luck Studying :)
