The ratio of the ages of Mary to that of her brother at present is 8 ∶ 7 and the ratio of ages of Mary’s brother to that of their mother 5 ∶ 9. If the difference between the ages of Mary and her mother is 23, what is the age of Mary’s mother?
1
63 years
2
72 years
3
56 years
4
68 years
5
70 years