What I got for the tip was: $2.60
This is what I did:
I made a proportion, x being the tip
22 x
----= ------ <------- here I did cross products (22*11.81=100x)
100 11.81
259.81=100x <-------- then I did inverse operations to solve the equation
x= 2.5982 <------- then I rounded since we're working with money
x= $2.60
Hope this helps :)