So we know that the Bruno's BAkery uses 4/9 barrels and that Cosmo's Bakery uses 6/5 as much. So we have to multiply 4/9 * 6/5 which is equal to 0.53 for one day.
Since they are asking for the 3/7 of the week we multiply 3/7 *0.53.
This is equal to 0.23 or 23/100
:3