Answer:
marcia must have sold at least 22 chocolate cones.
Step-by-step explanation:
Jan sold a total of 65 cones (20+15+30). Tomas sold a total of 68 cones (20+18+30).
If Marcia sold more cones than Jan or Tomas, she had to have sold more than 68 cones in total. 30+17 = 47. I subtracted 68-47, to see how many chocolate cones she should have sold to match the number of cones Tomas sold, which is 21 chocolate cones. Therefore, to surpass Tomas in the total number of cones sold, she had to have sold at least 22 chocolate cones.