Solution: If a box of biscuits costs X yuan, a bag of milk costs (10-0.8-0.9x) yuan.

List inequalities according to the meaning of the question:

x+( 10-0.8-0.9x)> 10

Solution: x > 8

X should be a positive integer of 9.

10-0.8-0.9×9= 1.7

A: A box of biscuits 9 yuan and a bag of milk 1.7 yuan.