Answer:
Yes, her calculation is correct. The value of 40% of 75 is 30.
Step-by-step explanation:
The value of 40% of 75 is

The value of
of 75 is

From the above calculation it is noticed that the value of 40% of 75 and
of 75 are same, therefore the calculation is correct and the value of 40% of 75 is 30.
The speed is the ratio between the distance and the time:

Data:
d=6343miles
t=9h

Then, the plane traveled at a speed of 704.77 miles per hour.
Answer:
142°
Step-by-step explanation:

Answer: x = -5, 3/2 y = 10, 7/2
Explanation:
y = 2x^2 + 6x - 10 (1)
y = - x + 5 (2)
=> 2x^2 + 6x - 10 = - x + 5
2x^2 - 7x - 15 = 0
(2x - 3)(x + 5) = 0
=> 2x - 3 = 0
2x = 3
x = 3/2
=> x + 5 = 0
x = -5
According to (2):
y = -x + 5
y = -(-5) + 5
y = 5 + 5 = 10
y = -x + 5
y = -(3/2) + 5
y = -(3/2) + 10/2
y = 7/2