Distance , d = a+b

The unit of d is in meter and t is in seconds.
So the unit of a a must be meter.
Now we have unit of b

is meter.
So unit of b*

= meter
Unit of b = meter/

So unit of a = m and unit of b = m/

.
It lets the viewer know it's something to do with underwater.
The answer is a.12.5kg because i just did the test and it was correct.
hope this helps
Answer: Gamma rays, x-rays, ultraviolet rays, visible light, and infrared rays.