**(1 to 15)**.

Erase 3 numbers so that remaining integers can be arranged as a**
3 by 4** array in which
the sum of the numbers in each row is a certain** S _{r}** and in each of the
columns a certain

**S**.

_{c}Present the triplet you have chosen and one of the possible arrangements.

D4. Bonus question:

How many distinct solutions are there?