The total number of students in a class is 65. If the total number of girls in the class is 35, then the ratio of the total number of boys to the total number of girls is:

6 : 7

Number of boys = Total number of students - Number of girls 

                        = 65 - 35 = 30

Ratio of no. of boys : no. of girls = 30 : 35 = 6 : 7