This entire statement is a mathematical expression. Start with an opening Nemeth Code indicator and a space; end with a space and a Nemeth Code terminator. Embedded or displayed, you will need to start a new line with the comparison sign (equals) and also start a new line with the operation sign (diagonal fraction line).
Using the example in your post, fraction indicators are not used because the numerator and denominator are each printed on the baseline of writing and there is no difference in type size. The letter E in the numerator does not need an English-letter indicator because it is not followed by a space. (Even though it will end the braille line, it would not be followed by a space were it touching the fraction line.) All words will be uncontracted.
This simbraille uses a 40-cell line.
.K NUMBER OF OUTCOMES CORRESPONDING TO
THE EVENT ,E
_/TOTAL NUMBER OF EQUALLY LIKELY