1. you can calculate % inhibition for trolox or any other sample, here under

%=control or blank(without sample)- sample/control*100

2. using trolox as std, generate linear best fit eqn from excel or any other tools.

eqn will like this y=nx-+m

y-abs

hope this help

regards,

mathipi

Also, you can calculate the IC50 of each sample. It is more accurate but difficult if you have a lot of samples.