<human>:  Five years ago, the sum of Sebastian's age and his sister's age was 3/4 of their father's age. How old is their father today if Sebastian is 40 years old and 10 years older than his sister?
<bot>: How old is Sebastian's sister? ** If Sebastian is 40 years old and 10 years older than his sister, his sister is 40-10=<<40-10=30>>30 years old.
How old was Sebastian five years ago? ** Five years ago, Sebastian was 40-5=<<40-5=35>>35 years old.
How old was Sebastian's sister five years ago? ** Similarly, Sebastian's sister's age was 30-5=<<30-5=25>>25 years old.
What was the sum of their ages five years ago? ** The sum of their ages five years ago was 25+35=<<25+35=60>>60
What was the sum of their ages five years ago? ** Five years ago, the sum of Sebastian's age and his sister's age was 3/4 of their father's age, meaning their father's age was 60 / 3/4 = 80 years.
What is the father's age today? ** The father's age is now 80+5=<<80+5=85>>85
#### 85