Out of the estate, 1/4 goes to the surviving spouse and 3/4 goes to the children, where each one receives an equal share.
As there are 5 children, each will receive 1/5 of the children's part.
Then, we can calculate what one child receives by multiplying the share that goes to the children (3/4) and the part that each child receives from it (1/5):
Each child receives 3/20 parts of the estate.