The number of ways that 30 mangoes can be distributed among 5 boys if each boy is eligible for any number of mangoes is 

Number of mangoes = n= 30

Number of boys        = r = 5

Number of ways of distributing n identical things to r persons so that each gets any number 

$=\mathrm{n}+\mathrm{r}-1_{{\mathrm{C}}_{\mathrm{r}-1}}={(30+5-1)}_{{\mathrm{C}}_{5-1}}={ }^{34}{C}_4$