1/5.
If 4 pieces of gum are each divided into 5 parts, that will mean there will be 20 smaller parts (5*4=20).
Each person will get one part of each piece of gum. If there are 4 pieces of gum originally, this means each person gets 4 small pieces of gum
If each person gets 4 small pieces of gum and there are 20 small pieces altogether, that makes the fraction 4/20
Since 4 and 20 are both divisible by 4, that makes the simplified answer 1/5.