Use below condition first in addition to above 2 conditions -
Mail to be sent to Maths == 'Yes' and Mail to be sent to Science == 'Yes' and IsmailsentMaths == 'No' and IsmailsentSci == 'No'
Use below condition first in addition to above 2 conditions -
Mail to be sent to Maths == 'Yes' and Mail to be sent to Science == 'Yes' and IsmailsentMaths == 'No' and IsmailsentSci == 'No'