The average weight of the students in four sections A, B, C and D is 55 kg.…

The average weight of the students in four sections A, B, C and D is 55 kg. The average weights of the students of sections A, B, C and D are 45 kg, 40 kg, 75 kg and 85 kg respectively. If the average weight of the students of sections A and D together is 65 kg and that of B and D together is 55 kg, then what is the ratio of the number of students in A and C?