Maria has 24 dollars, every one of her siblings has 12 dollars. how many dollars she had to give to each of her siblings so that everyone of four siblings have same amount?
I assume that she is one of the 4 siblings:
each has $12 including Maria, once she keeps her $12 she will have $24-$12 = $12 to distribute 4 ways:
So Maria Keeps her $12 + $3 = $15 and she give each or her other three siblings $3, now all four siblings have $15.