Pebble falls into the pond from the surface and it descends at a rate of 2 feet per second.
So basically, the pebble is descending or falling down at 2 feet per second which means after every 1 second, it goes 2 feet down.
The equation to represent the depth of the pebble with time is given by:

Where, 'd' is the depth after certain time and 't' is the time in seconds.
Now, we need to find the depth of the pebble after 5 seconds.
Plugging the value
, we get:

So, after 5 seconds the pebble will be at the depth of 10 feet.