Subtract till 100

Calculate:

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

47	-	17	=
35	-	30	=
63	-	44	=
88	-	19	=
85	-	35	=
51	-	5	=
34	-	14	=
86	-	40	=
97	-	47	=
48	-	39	=