i answerd under 580000 but it is wrong why

Mahler, Inc., applies manufacturing overhead at the rate of $40 per machine hour. Budgeted machine hours for the current period were anticipated to be 120,000: however, a lengthy strike resulted in actual machine hours being worked of only 90,000. Budgeted and actual manufacturing overhead figures for the year were $4,800,000 and $4,080,000, respectively. On the basis of this information, the company's year-end overhead was: overapplied by $580,000. underapplied by $580,000. underapplied by $480,000. underapplied by $900,000. overapplied by $1,200,000