Answer:
11.7%
Step-by-step explanation:
let´s first calculate the initial invested money, it envolves the margin account plus the shares bought:

Capital(t=0)=3,428
so it means in the margin account there are left 1,428. Now let´s calculate the amount of money a year later:
Capital(t=1)=200*12 + 1,428
Capital(t=1)=3,828
Finally we can now calculate the return after a year:


return=11.7%