I will paraphrase what Lasha said:
Before the discussion you shoule understand such a problem:
we won't take ladies with white handbags and rings into account,there are 60 ladies with umbrella and 75 with black shoes,then how many ladies with both?
with umbrella----------------60
with black shoes-------------75
Totol--------------------------100
we obtain
with umbrella and without black shoes-------------------------100-75=25
considering that:with umbrella----------------60
wo obtain
with both -----------------------------------60-25=35
I think after you understand this point,you can solve it.