How to use variable in sed command

I am trying to delete two lines ( 7 and 8) from a .txt file. For this I am using following code:-

#!/bin/sh
Column="7"
sed '"$Column",8d' myfile.txt > result.txt

on running this script, I am getting this error:-

sed: -e expression #1, char 1: unknown command: `"'

Please tell me how to use variable as a part of sed command.