Answer:
Speed of plane in still air = 825 km/h
Step-by-step explanation:
Given:
Speed of plane with the wind is 145 km/h faster than what it would have with still air.
Speed of plane with wind = 970 km/h
To find speed of plane in still air.
Solution:
Let speed of plane in still air be =
km/h
Thus speed of plane with wind would be given as =
km/h
Speed of plane with wind is given =970 km/h
So, we have:

Solving for
.
Subtracting both sides by 145.

∴
km/h (Answer)
Thus, speed of plane in still air = 825 km/h
Answer:
6 dollars and 67 cents
Step-by-step explanation:
Answer:
87.5
Step-by-step explanation:
By completing the square,
y
=-14x^2+70x
=-14(x^2-5x)
=-14(x-5/2)^2+175/2
the max. height=175/2
i.e. 87.5