### Instruction: Enrico makes a list of the first twenty positive multiples of 3. Marie makes a list of the first ten positive multiples of 6. How many of the numbers on Marie's list are also on Enrico's list?### Response: I need to compare the two lists and see which numbers they have in common.
Enrico's list is 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60.
Marie's list is 6, 12, 18, 24, 30, 36, 42, 48, 54, 60.
I notice that every multiple of 6 is also a multiple of 3, so every number on Marie's list must also be on Enrico's list.