Part A: 12 times it was heads out of 20. So to find the experimental probability, you would take the number of times it landed heads and divide it by the number of times it was fliped. So the answer to Part A would be 12/20 = 3/5
Part B: Theoretical probability is when an event is completly random, the times something should happen out of so many times is the theoretical probability. For example, in a completly random world where everythin were to be random, a coin flipped would land exacfly 1/2 the time heads and 1/2 the time tails.
Hope this helps!