Answer:
35% is not installed
Explanation:
Since there are twenty tiles, 20 times 5 is 100, you do this because you want to get a percent out of 100. If you do 13/20, whatever you do to the bottom applies to the top. So multiple 13/20 by 5/5 to get 65/100 or 65% of the tiles are installed. there are 7 uninstalled tiles. 7/20*5/5(to get a percent out of 100%) is 35/100 or 35%. So the percentage of uninstalled tiles is 35% while 65% of the tiles are installed. To check this, add 35% to 65% and it equals 100%. (Showing that your answer has to at least be reasonable)!