Answer:GCF is the Greatest Common Factor. So what you have to do is find the greastest factor 12 and 21 has in common.
Step-by-step explanation: go to learnzillion.com
A Little but not that much so im straight
Its 80 because if you find perfect square around the number 80 you'd get
√64 and √81
which would be 8 and 9
21
Turn 75%into a decimal 0.75 than multiply that by 28
