For this case we have to, by definition:
1 Kilogram is equivalent to 1000 grams
If Ali bought 3 kg of mandarin orange, we make a rule of three to determine how many grams are:
1 kg ------------> 1000 g
3 kg ------------> x
Where "x" represents the amount of grams that Ali bought.
![x = \frac {3 * 1000} {1}\\x = 3000 \ grams](https://img.qammunity.org/2020/formulas/mathematics/middle-school/vupjjqn8kriblxvy09971ag04bj51ihcbu.png)
If Mia bought 3250 grams of mandarin oranges, and we want to know how many grams I buy more than Ali, we subtract:
![3250 \ g-3000 \ g = 250 \ g](https://img.qammunity.org/2020/formulas/mathematics/middle-school/cuce8i43pgizx46fatjnhzrxisdyixkh29.png)
So, Mia bought 250 grams more mandarin orange than Ali.
Answer:
250 grams