2 x 100 + 5 x 10 + 2 = 252
_______
75 | 18909
| 15000
_______
| 3909
| 3750
_______
| 159
| 150
_______
| 9

Count of mangoes to distribute = 18909
_______
First we give 2 x 100 mangoes to each of 75 boyes
So, we have taken 15000 manogoes out of all the mangoes = 18909 mangoes
_______
Count of mangoes remaining = 3909 mangoes
Then we give 5 x 10 mangoes to each of 75 boyes
So, we have taken 3750 manogoes out of remaining mangoes = 3909 mangoes
_______
Count of mangoes remaining = 159 mangoes
Then we give 2 mangoes to each of 75 boyes
So, we have taken 150 manogoes out of remaining mangoes = 159 mangoes
_______
Count of mangoes remaining = 9 mangoes