Envision Math 2.0: Grade 7, Volume 1
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Envision Math 2.0: Grade 7, Volume 1 View details
3. Add Integers
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Exercise 10 Page 23

Practice makes perfect
We want to find the integer that represents the airplane's change in altitude to avoid the storm. Let's use a number line to visualize the given situation. From the exercise, we know that the airplane was flying at an altitude of 30 000 feet. It then flew up to 38 000 feet. Let's list the steps we will follow to create the number line.
  • First, we start at 30 000, which represents the initial altitude of the airplane.
  • Then, we move to 38 000. This represents the airplane flying up to 38 000 feet.

Let's mark these steps on the number line.

As we can see from the graph, 38 000 is 8000 units to the right of 30 000. Because of this, we can say that the integer 8000 describes the airplane's change in altitude to avoid the storm.

Now we want to find the integer that represents the airplane's change in altitude after passing the storm. We can follow the same process we used in Part A. We know that the plane started at 38 000 feet, after it rose up to avoid the storm. After passing the storm, the plane immediately returns to its initial altitude of 30 000 feet. Let's list the steps we will follow to create the number line.
  • First, we start at 38 000, which represents the altitude of the airplane before it descends.
  • Then, we move to 30 000. This represents the airplane flying back down to its original altitude.

Let's mark these steps on a number line.

As we can see from the graph, 30 000 is 8000 units to the left of 38 000. Because of this, we can say that the integer - 8000 describes the airplane's change in altitude immediately after passing the storm.

Finally, let's draw a number line to represent the airplane's total change in altitude. Let's start by creating a list of steps that represent the airplane's flight. Let's take a look at the list of steps we need to follow to create a number line.
  • First, we start at 30 000, which represents the initial altitude of the airplane.
  • Then, we move to 38 000. This represents the airplane flying up to 38 000 feet.
  • Finally, we move to 30 000. This represents the airplane descending to its original altitude.

Let's mark these steps on the number line.