Work A Work B Total

Estimated total machine-hours used 2,500 1,500 4,000

Estimated total fixed manufacturing overhead 11,500 15,900 27,400

Estimated variable manufacturing overhead per machine-hour 2.00 2.80

Question : What is the plantwide predetermined overhead rate?

I am not sure how to solve this problem when the "Estimated variable manufacturing overhead per machine-hour" for work A and B is different