Question

Rolls are being prepared to go to grocery stores. Divide 72 rolls into 2 groups so the ratio is 3 to 5.

Answer 1

To do this, nice it to add 3 and 5, then divide 72 by the result of sum 3 and 5. Finally multiply it by 3 and by 5 to get the result.
Lets do this
3+5=8
72:8=9 - number of rolls in 1 "unit" 
9*3=27  - first group
9*5=45  - second group