Subtract till 100

Calculate:

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

71	-	15	=
87	-	38	=
28	-	17	=
98	-	47	=
69	-	2	=
49	-	46	=
20	-	18	=
49	-	9	=
32	-	25	=
32	-	28	=