First, we can divide the numerator and denominator by 2 to get
(4+i)/(2-4i)
Now, multiply the numerator and denominator by the conjugate of the denominator, 2+4i:
[(4+i)(2+4i)]/[(2-4i)(2+4i)] = [8+18i+4i2]/[4-16i2] (NOTE: i2=-1)
= (4+18i)/20
= (4/20) + (18/20)i = (1/5) + (9/10)i