Using the given table,find the amount of added iron in each solution?

Sample name	Volume (ml) of 2% hydroxylamine hydrochloride	Volume (ml) of 12% sodium acetate	Volume (ml) of 2mM phenanthroline	Volume (ml) of iron tablet sample solution	Volume(ml) of iron standard solution
Blank	1.00	2.50	2.50	0.000	0.000
Unknown	1.00	2.50	2.50	0.100	0.000
+1	1.00	2.50	2.50	0.100	0.100
+2	1.00	2.50	2.50	0.100	0.200
+3	1.00	2.50	2.50	0.100	0.300
+4	1.00	2.50	2.50	0.100	0.400
+5	1.00	2.50	2.50	0.100	0.500