Tom has a bag filled with 10 green balls, 5 red balls and 5 blue balls, what part on toms bag has green balls

Add up all the marvels and then divide the number of green balls by the total.

10/(#ofgreen+#ofred+#ofblue). If you want it as a percent just multiply the decimal by 100. I would look like {10/(#ofgreen+#ofred+#ofblue)} *100