A static route adds an entry to the routing table for a specific destination IP address or subnet.
To route traffic to the 10.10.20.0/24 subnet through the IP address 192.168.100.1:
conf t
ip route 10.10.20.0 255.255.255.0 192.168.100.1
The netmask 255.255.255.0 means the same as the subnet/24 notation.