The answer is 12. By using division, & backing into the number, you can find the GCF of both numbers. This means 12 is the highest number you can multiply by a number to get both 84 and 36.
The answer is 4. By using the factor tree method, you can figure out the GCF of each number. This means 4 is the highest number you can mulitply anything by to get both 84 and 36.