Finding the maximum value.

Hi everyone. this should be an easy one but its escaping me.

I need to find the maximum value per account across two dimensions, position and entity, excluding missing values

For our salary planning application, an employee can have more than one position in more than one entity throughout the year. I need to find the value, not the position or entity.

for example john doe works as a laborer in the yard and a driver in the carpool. His wage in the yard is $25 while his wage as a driver is $30. For overtime, his rates are $33 / $32 respectively, all values are fictional.