The rise or an increase in altitude is represented by positive sign and a decend or decrease in altitude is represented by negative sign.
First the helicopter descended 1200 feet. So the change in altitude will be -1200 feet.
Then the helicopter rose by 800 feet. So the change in altitude will be 800 feet.
Finally the helicopter descended by 450 feet. So the change in altitude will be -450 feet.
The net change in altitude will be the sum of all the above 3 changes.
Change in altitude = -1200 + 800 - 450 = -850 feet
The negative sign indicates a descend i.e. loss in altitude. So the net change in altitude was a loss of 850 feet.
Answer:
D.16.5m
because circumference=21/7×5.25
=16.5m
Answer:
22. Perimeter = 52 units
Area = 160 Square Units
23. Notation form : 
Standard Form : 200000
Step-by-step explanation:
22.
The formula for perimeter is
P = 2 (length + Width )
= 2 ( 2x+3x+1)
= 2(5x+1)
The Formula for Area of a rectangle is
A= length x width
A= 
A=
Now we have to find the Perimeter and Area for x = 5
P = 2(5 x 5 +1)
P= 2(26)
P=52 units
A= 6 x 5 x 5 + 2 x 5
A= 150 + 10
A= 160 square units
23.
A. By using rule of exponents , we can determine that both the results will be same.
B.
Miriam's calculation



Priya's calculation



Standard notation

Answer:
Add the numbers together and divide by the number of numbers. (The sum of values divided by the number of values). Arrange the numbers in order, find the middle number. (The middle value when the values are ranked).