Question 351073
Assuming the length to be the longer dimension:
There is a 8*6=48 cm^2 printed area equidistant from all sides. The length has to be 2 cm longer than the width because the page is 2 cm longer than the width and the margins must be the same width. 
16-2x=8
-2x=-8
x=4 cm The margin width.
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Ed