Question

Mr. Riley dove off a cliff that was 30 feet above the surface of the water and descended a total of 100 feet. Which of the equations below can be used to determine his elevation at the bottom of his dive?

a) 30 + 100
b) 30 - 100
c) 30 + (-100)
d) Both b and c

Answer 1

Mr. Riley's elevation at the bottom of his dive is determined by the equation 30 - 100, which can also be written as 30 + (-100). Both result in an elevation of -70 feet below sea level.

Step-by-step explanation:

To determine Mr. Riley's elevation at the bottom of his dive, we should take the initial elevation above the water and subtract the total distance descended. Mr. Riley started at an elevation of 30 feet above the water surface and descended 100 feet. Since descending is going downwards, it is represented by a negative movement relative to the starting position. Therefore, the equation that can be used to find his elevation at the bottom of the dive is 30 - 100, which simplifies to -70 feet. This means Mr. Riley is 70 feet below the sea level at the bottom of his dive. Options b and c are both correct since they mathematically represent the same operation; 30 plus a negative 100 is the same as subtracting 100 from 30.