if we write the ratio 15 cookies to 40 cookies we will get the following ratio
15:40
to write in simplest form we have to find the highest common factor for both 15 and 40
the factors for both 15 and 40 are as follows
15 - 1,3,5,15
40 - 1,2,4,5,8,10,20,40
the highest common factor is 5
so we have to divide both ny 5 to get the simplest form

ratio in the simplest form is 3:8