Sebastian was in a hotel lobby and took the elevator up 8 floors to his room. Then he took the elevator down 5 floors to the parking garage. He described his movement with the expression below.

Question

5+(−8)



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(1 point)
Responses

Sebastian should have switched the two addends and written −8+5
.
Sebastian should have switched the two addends and written negative 8 plus 5.

Sebastian should have started at zero before adding –8.
Sebastian should have started at zero before adding –8.

Sebastian should have used 0 and –8.
Sebastian should have used 0 and –8.

Sebastian should have used –5 and 8.

Answer 1

Let's break down the movement:

1. Sebastian starts at the ground level (which we can think of as 0).
2. He goes up 8 floors, resulting in 0 + 8 = 8.
3. Then, he goes down 5 floors, resulting in 8 - 5 = 3.

The expression 5 + (−8) suggests starting at 5 floors above the ground, and then going down 8 floors. However, he was not at 5 floors; he was at 0 floor before his movements started.

So, his movement should actually reflect moving from 0 to 8 (up 8), and then from 8 down to 3 (down 5), which could be expressed correctly as:

0 + 8 + (-5)

From your given options, the best response to describe the mistake in Sebastian’s expression, is:

Sebastian should have started at zero before adding –8.

This implies that he should have considered the ground level as a starting point (0) before going up and down.