Answer:You can put this solution on YOUR website!
anna's weight = a
her sister's weight = s
a = 3 + s
a + s = 105
3 + s + s = 105
3 + 2s = 105
2s = 105 - 3
2s = 102
s = 102/2
s = 51
a = 3 + 51 = 54
so, Anna's weight = 54 kg, her sister's weight = 51 kg
