Hello!
To find the difference, you must subtract (since the difference is the answer to a subtraction question)
26.22 -- 3.09 = 23.13
To find the sum, you must add (since the same is the answer to an addition question):
3.057 + 2.08 + 11.5 + 16.712 = 33.349
And those are your answers! ^ I hope this helped you! :)
Also, the answer to a multiplication question is called the 'Product' and the answer to a division question is called the 'Quotient'.