"Quotient" means the result of division (in the same way that "sum" means the result of addition) so we know we're going to write a fraction.

One part of the fraction is a number less seven, which is better phrased as a number minus seven. The other part of the fraction is twenty.

( N - 7 ) / 20

Hand-written, that's better represented by "N - 7" centered above a horizontal fraction line, and "20" centered below. Typed, the parentheses make the difference between this and the expression spoken as "seven-twentieths less than a number".