How many valid subnets do you get if you borrow 3 bits?

When you borrow 3 bits from the host portion of an IP address, you can create (2^3 = 8) valid subnets. However, one subnet is reserved for the network address and another for the broadcast address, leaving you with 6 usable subnets. Thus, by borrowing 3 bits, you obtain 6 valid subnets for use.