For Surbhi:
Dearness allowance = ₹Y
Basic salary = 100/25 * Y = ₹4Y
Total salary = 12500
Y + 4Y = 12500
Y = 2500
Dearness allowance = ₹2500
Basic salary = ₹10000
For Deepa:
Dearness allowance = ₹2100
Basic salary = 100/25 * 2100 = ₹8400
Total salary = 2100 + 8400 = ₹10500
Let the items A and B sold by Deepa is 'p' and 'q' respectively.
p * 12% of 8400 + q * 15% of 8400 = 6300
4p + 5q = 25
p = (25  -  5q)/4 = 5(5  -  q)/4
Here 5  -  q must be divisible by 4.
So, q = 1 => p = 5*(5  -  1)/4 = 5
So, items A and B sold by Deepa is 5 and 1 respectively.
For Maya:
Basic salary = 130% of Surbhi's basic salary = 130% of 10000 = ₹13000
Dearness allowance = 25% of 13000 = ₹3250
Total salary = 13000 + 3250 = ₹16250
Let the items A and B sold by Maya is 'r' and 's' respectively.
r * 12% of 13000 + s * 15% of 13000 = 12480
4r + 5s = 32
s = (32  -  4r)/5 = 4(8  -  r)/5
Here 8  -  r must be divisible by 5.
So, r = 3 => s = 4*(8  -  3)/5 = 4
So, items A and B sold by Maya is 3 and 4 respectively.
In tabular form - 
| Person | Total salary | Dearness allowance | Basic salary | Total incentive | Item A | Item B | 
| Maya | 16250 | 3250 | 13000 | 12480 | 3 | 4 | 
| Surbhi | 12500 | 2500 | 10000 | - | - | - | 
| Deepa | 10500 | 2100 | 8400 | 6300 | 5 | 1 | 
| Rakhi | X | - | - | 12240 | - | - | 
Average of basic salary of Maya and Deepa together = (13000 + 8400)/2 = 10700
Average of total incentive got by Maya and Surbhi together = 10700 * 100/107 = 10000
Total incentive got by Surbhi = 2*10000  -  12480 = ₹7520