Answer:
write out the multiples of 3 and 7 between 1 and 100 and those that overlap are the ones with the stars and circles.
Explanation:
3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,51,54,57,60,63,66,69,72,75,78,81,84,87,90,93,96,99
7,14,21,28,35,42,49,56,63,70,77,84,91,98
21,42,63,84