The following are the results of the retinoscopy on a 20 year-old man using 
a streak retinoscope. (assuming a working distance of 2/3 metre)
 

OD With the streak in the vertical meridian and sweep horizontally, the retina

       reflex is neutralized with +0.50D.
       With the streak in the horizontal meridian and sweep vertically, the retina
       reflex is neutralized with -1.00D.
 

OS  With the streak orientated at 30^o and sweep at 120^o, the retina reflex

       is neutralized with +1.00D
       With the streak orientated at 120^o and sweep at 30^o, the retina reflex
        is neturalized with -0.50D

a. Draw the power cross (taking into account the working distance). 

b. Write down the glasses prescription for this patient (using negative cylinder).