Final answer:
The statement that is true is that 40 campers know how to swim, as we subtract the 20 campers who do not from the total of 60 campers at Camp Topanemus.
Step-by-step explanation:
The student's question asks about the number of campers at Camp Topanemus who can swim. According to the given information, there are a total of 60 campers, and 20 of those do not know how to swim. To find out how many campers know how to swim, we subtract the number of campers who can't swim from the total number of campers. Therefore, the calculation would be 60 (total campers) - 20 (campers who can't swim) = 40 campers who know how to swim. Among the given statements, number 2) '40 campers know how to swim' is the true statement.