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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.
It's x = 4 and y = 2.
3(4) + 4(2) + 6 = 12 + 8 + 6 = 26