What is the binart equivalent to the dotted decmal net mask-225.225.192.0?
That's not a valid subnet mask. Probably the subnet mask is
supposed to be 255.255.192.0.
You can convert each of the parts separated by dots to binary
separately. Just use a scientific calculator, for example, the one
that comes with Windows.
To be a valid subnet mask, the binary equivalent must have a
certain number of only ones, followed by only zeros.