2 Networks because the link between the routers is on one subnet, the other subnet connects to Fa0/0.

The subnets would be 192.168.26.0/25 and 192.168.26.128/25

Borrowing 1 bit which is the first bit after the 24th, that bits value is 128, the subnet mask would be 255.255.255.128

Add the bits that are left over, they will equal 128, there are 256 addresses possible, 256 divided by 128=2...each of these subnets are 128 addresses apart

Another Example:

If you borrowed 2 bits, you would have 4 networks: 2 bits=192; add the remaining bits which is 64, 4 x 64=256, for every 64 host the network address would change.

The 4 networks would be 192.168.26.0/26, 192.168.26.64/26, 192.168.26.128/26, 192.168.26.192/26....each of these subnets are 64 addresses apart

Remember each octet is has a value of 256

11111111.11111111.11111111

11111111.11111111.11111111

I hope I didn't confuse you too much, subnetting is complicated in itself, explaining it I think is more complicated.