Question about this equation

15x-34=16

First I added 34 to both sides

15x=50

I divide both sides by 50.

x= 3.333333333

My assignment says this is wrong, “Write your answer in the form of a fraction, integer, or exact decimal. Do not approximate.”

My question is how do I turn 3.33333 into a fraction? After looking it up I know the fraction is 10/3. But how do i figure that out myself?