Consider the following oxides:
V_2O_5, Cr_2O_3, Mn_2O_7, V_2O_3, VO_2
A number of oxides which are acidic is \( x \).
Consider the following complex compound:
[Co(NH_2CH_2CH_2NH_2)_3](SO_4)_3
The primary valency of the complex is \( y \).
What is the value of \( x + y \) is?