A consumer faces a trade-off between labor and leisure. Suppose the consumer receives a raise and starts earning a higher wage. Based on the Slutsky equation, the substitution effect with respect to leisure due to this change is -15.00. However, due to the change in income, his consumption increases by 3.00 units. If this consumer can work or rest a maximum of 24 hours, how many hours must he have been working if this change in his wage doesn't lead to a change in his hours worked