The share of A: B is 3: 4
The share of B: C is 2: 3
Note: Whenever such form is given, multiply a to b, then b to b, and then b to c.
i.e., A: B: C = 3*2: 4*2: 4*3
Or, A: B: C = 6: 8: 12
Or, A: B: C = 3: 4: 6
Sun of ratios = 13
Now, the share of B = [4/13] * 7800 = 2400
Share of C = [6/13]* 7800 = 3600
The difference between the share of B and C = 3600- 2400 = 1200