Subtract till 100

Calculate:

The number of examples:
Numerical difficulty:
Range of values:
Multiplicity:

93	-	20	=
93	-	6	=
99	-	23	=
87	-	21	=
59	-	24	=
82	-	24	=
46	-	10	=
37	-	11	=
78	-	6	=
75	-	45	=