How do you find internal energy of U=Q+W?

[nrc_8706]

i figured out that
Wac=21000J
Wbc=0
Wab=91000J

how do you find internal energy of U=Q+W?

 

[lightgrav]

It is the CHANGE of Internal Energy that is a process quantity,
related to other process quantities like Work and Heat.
If this is a "thermally isolated system" or the steps happen "quickly",
then you treat Q = 0 . If it happens "slowly" or at known Temperature,
then you know T and should calculate I.E. from T (depending on the kind of gas)