To answer this question you will divide the total amount of mulch into groups that are the size of the amount of mulch needs for each flower bed.
So, 3/4 divided by 1 1/6 ton. Because the amount you are dividing by is bigger than the amount you started with, your answer will not be one full garden bed.
3/4 divided by 1 1/6 can be rewritten as 3/4 divided by 7/6, and then as 3/4 x 6/7. The answer is 9/14 of a garden she can put mulch on.