Let's see -
Since a variable next to a number means to multiply, we'll do the opposite for solving what d is.
°° Dividing both sides by 4.8 -

d = 0.25
So, your final answer is 0.25
If you wanted to make this decimal into a fraction, you would just say:

If you wanted to make this into a percent, however, you could multiply the 0.25 by 100, which would give us 25%.
↑ ↑ ↑ Hope this helps! :D