Jawapan

2016-03-19T13:15:39+08:00
Serena 10th birthday means she was 10 and her mom was 3 times as old which is 30. They are 20 years apart so 0.5 or 1/2 her mom's age will be Serenas age when her mom is 40 and she is 20
2016-03-19T13:16:12+08:00