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: 24 minutes!
Step-by-step explanation: As mentioned, it can eat 45 ants per minute, How long would it take to eat 1,080 ants?
It's simple, just divide 1080 by 45 and when you divide it, the answer is 24!
The missing numbers would be 12-6
