W = 6 · 10^6 J (side note - it's joule, not jewel)
U = 220 V
t = 30 min = 1800 sec
I = ?
We'll start from the electric energy equation:
W = U · I · t
Now to get the I, we need to divide both sides of the equation by (U · t):
I = W / (U · t)
Now, let's see if our data is in SI units. Work (same as energy) in joules and voltage in volts are OK. Time needs to be converted into seconds:
t = 30 min = 30 * 60 sec = 1800 sec
Now we're ready to insert our data:
I = 6,000,000 [J] / (220 [V] · 1800 [s]) = 6,000,000 [J] / 396,000 [V·s] ≈ 15 [A]
Answer: The dryer draws approx. 15 amperes.