Given :
A boat is located a sea level. A scuba diver is 80 feet along the surface of the water from the boat and 30 feet below the water surface.
A fish is 20 feet along the horizontal plane from the scuba diver and 10 feet below the scuba diver.
To Find :
The slope between the scuba diver and fish.
Solution :
Horizontal distance between diver and fish is 20 feet.
Fish is 10 feet below the scuba diver.
Slope between scuba diver and fish is :

Therefore, the slope between the scuba diver and fish is 0.5 .
Answer:
If the use the method ''Add -5 to both sides, then multiply both sides by -2/7'', we can get the value n = 6.
Thus, the correct option is 'C'.
Step-by-step explanation:
Given the equation

Let me solve this using the correct method

Add -5 to both sides

simplify

Multiply both sides by -2/7

simplify

Therefore, if the use the method ''Add -5 to both sides, then multiply both sides by -2/7'', we can get the value n = 6.
Thus, the correct option is 'C'.