Answer:
The wieners come in packages of 12 and the buns in packages of 8. Then we must find the common multiple of 8 and 12 that is closest to 100 (because the want to make about 100 hotdogs)
then the multiples of 12 are next to 100 are:
12*10 = 120
12*9 = 111
12*8 = 99
and the ones for 8 are:
we already know that 8*12 = 99, so we try with 13:
8*13 = 104
then they need to buy 9 packages of wieners and 13 packages of buns, the number of hotdogs that they can make is equal to 104, and with a:
111 - 104 = 7 wieners leftovers