Question

Every sixth visitor to an animal shelter gets a free animal calendar.every twentieth vistor gets a free animal toy.which visitor will be the first to get both

Answer 1

You will need to find the lowest common multiple.
6 = 2 x 3
20 = 2 x 2 x 5
LCM = 2 x 2 x 3 x 5 = 60
The 60th visitor will be the first to get both.