Multiple Choice Question

A purchaser is offered a $2\%$ discount if the bill is paid within $7$ days, otherwise, the full amount is due in $30.$ This purchase discount is expressed on the invoice as

$\frac{2}{7},\frac{n}{30}$

$\frac{n}{2},\frac{7}{30}$

$\frac{n}{7},\frac{2}{30}$

$2/30,$ n$/7$