Final answer:
The least common multiple (LCM) of Meagan's lesson intervals, 13 days and 6 days, is 78. Meagan will have both piano and gymnastics lessons on the same day every 78 days.
Step-by-step explanation:
The question is asking to find the common multiple of the two lesson intervals: piano lessons every 13 days and gymnastics lessons every 6 days. To find when Meagan will have both lessons on the same day, we need to calculate the least common multiple (LCM) of 13 and 6.
- The multiples of 13 are 13, 26, 39, 52, 65, 78, and so on.
- The multiples of 6 are 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72, 78, and so on.
By examining the lists, we can see that the LCM of 13 and 6 is 78. Therefore, Meagan will have both piano and gymnastics lessons on the same day every 78 days.
The correct answer is c) Every 78 days.