The elementary school lunch menu repeats every 20 days ; the middle school lunch menu repeats every 15 days. both schools are serving pizza today. in how many days will both schools serve pizza again?

The trick to this question is the find the least common multiple of 20 and 15. You could do 20×3=60 and 15×4=60 as those both equal the same number yet you there are no other multiples they share before 60. So the next time the two schools will eat pizza on the same day again will be in 60 days. Hope this helps!