Okay, so given the annual salary is $50,000, that isn't what we want to find, we want to find the disposable income by monthly. So what we start with first is dividing the annual salary by 12 months in order to find the salary of one month. Which is rounded off to $4167 per month. For Federal tax rate, 20% of $4167 is $833.40 and the State tax rate is $291.69. Since they are being deducted, you would need to subtract them from the monthly value which will eventually give you $3041.91. In this term, this will be technically the disposable income because it is after the taxes and the amount of money that is used for spending or saving, but if you want to deduct the money even more with the other prices, then the final answer would be $1656.91.