Two kids sit on a seesaw of length 4.2m, balanced at its center. Sarah sits at the far end and has a mass of 55.kg. The Anna is 75kg. They seesaw for a while (having a grand time) then decide to balance themselves. Anna is sitting from the center. Then Sarah is given a bag of oranges weighing 3.0kg, and the seesaw rotates out of balance. When the Anna is given a bag of apples, balance is still not restored. She needs to place the apples 0.25m behind her for them to be balanced again. What is the mass of the bag of apples?