Why Presidents cannot do or not their duties to interpreting law ?

Portia grant is an employee who is paid monthly. for the month of january of the current year, she earned a total of $8,388. the fica tax for social security is 6.2% of the first $118,500 earned each calendar year and the fica tax rate for medicare is 1.45% of all earnings. the futa tax rate of 0.6% and the suta tax rate of 5.4% are applied to the first $7,000 of an employee's pay. the amount of federal income tax withheld from her earnings was $1,391.77. what is the total amount of taxes withheld from the portia's earnings?