Finding distance between two origin points; waves

[Butterlegs]

1. A submerged scuba diver hears the sound of a boat horn directly above her on the surface of the lake. At the same time, a friend on dry land 22.0 m from the boat also hears the horn (Figure 1). The horn is 1.2 m above the surface of the water. What is the distance (labelled by"?" in Figure 1) from the horn to the diver? The speed of sound in water vwater = 1482 m/s.

I have absolutely no idea where to start with this. I am completely stumped. Any help would be greatly appreciated

 

[CompuChip]

So you know the speed of sound in water (and air, presumably) and you need to know the distance. What bit of information are you missing to convert a speed to a distance?
You should find that you can use the other given data (the friend at 22.0 m on dry land) to calculate this.

 

[Butterlegs]

I really don't know how I missed that.