Plz help I keep getting different answers

-12.6+(-8.7)

Step-by-step explanation:

Given : While scuba diving, Rajeev dove to a depth of 12.6 feet below the surface of the water and then descended another 8.7 feet.

To find : What expression can be used to find Rajeev’s new position?    

Solution :

Rajeev dove to a depth of 12.6 feet below the surface of the water.

i.e, it dove downward means -12.6 feet.

Then descended another 8.7 feet.

i.e, again he dove downward means -8.7 feet.

The expression used to find the  Rajeev’s new position is

y= -12.6 feet +(-8.7)feet

or y=-12.6-8.7

y=−21.3 feet

i.e, 21.3 feet down he is from the surface of water.

4 and 5)16.97 or 12√2

6)15.59 or 9√3

7)y = 15.59 or 9√3     x =27

8)17.80