Question
The brother is elder to his sister by 6 years. Seven years ago the product of their age was 72.what is the age of brother.
Answers
Damon
(b-7)(s-7) = 72
b = s+6
so
(s+6-7)(s-7) = 72
(s-1)(s-7) = 72
s^2 - 8 s + 7 = 72
s^2 - 8 s - 65 = 0
(s-13)(s+5) = 0
s = 13
then b = 19
b = s+6
so
(s+6-7)(s-7) = 72
(s-1)(s-7) = 72
s^2 - 8 s + 7 = 72
s^2 - 8 s - 65 = 0
(s-13)(s+5) = 0
s = 13
then b = 19