3 1/4 yards is written as 3.25
5/6 yards is written as 0.83
So you need 3.25 yards of fabric for your dress.
And, you need 3.25 - 0.83 yards of fabric for your jacket.
That's 2.42 yards of fabric.
Dress: 3.25 + Jacket: 2.42 = 5.67
To manufacture both pieces you need 5.67 yards of fabric.
Convert to metres
However, nowadays, fabric is often sold by the metre. Following the same pattern, to make your dress and matching jacket, you will need:
3.9718 metres for the dress and 2.2128 metres for the jackets.
What else?
Other factors to take into consideration are the stretch of your fabric. A very stretchy fabric can be cut slightly smaller for a sharper line. Also, a fabric with a complex fabric is both more difficult to cut accurately and more difficult to tailor.