Show me the steps to solve Autogas Corporation manufactures industrial$-$sized gas furnaces and uses budgeted machine hours to allocate variable manufacturing overhead. The following information relates to the company's manufacturing overhead data:

Budgeted output units $31,000$ units

Budgeted machine$-$hours $16,585$ hours

Budgeted variable manufacturing overhead costs for $16,585$ hours $$348,285$

Actual output units produced $33,000$ units

Actual machine$-$hours used $14,400$ hours

Actual variable manufacturing overhead costs $$384,000$

What is the flexible$-$budget variance for variable manufacturing overhead?