Billy is $\frac15$ of his brother's age. In $9$ years, Billy will be $\frac12$ of his brother's age. What is the sum of their current ages, in years?
b = 1/5 s s = sibling
b+9 = 1/2 (s+9) sub in the red equation
1/5s + 9 = 1/2s + 4.5
4.5 = .3s
s = 15 y/o b = 1/5 (15) = 3 y/o You can finish......
My brain is dead today. I did so much math and english and history. It can't hold anymore info. Please just tell me the answer.
Add what? 15 and 1/5?