To solve this problem you must apply the proccedure shown below:
1. Based on the problem above, you have that the width of the paper is:
[tex]8 1/2=17/2 in[/tex]
2. Geoff must leave [tex]3/4
[/tex] in margins on his paper. Therefore, he needs to put marks as a guide at:
[tex]3/4 inches=0.75 inches[/tex]
Therefore, as you can see above, the answer is: [tex]0.75 inches= 1.90 centimeters[/tex]