Answer:
Tanya is 14; Ruby is 11.
Step-by-step explanation:
Let T represent Tanya's current age and let R represent Ruby's current age.
We know that their ages add up to 25. So:
[tex]T+R=25[/tex]
8 years ago, Tanya was twice as old as Ruby. In other words, Tanya's current age minus 8 is the same as Ruby's current age minus 8 times 2. So:
[tex]T-8=2(R-8)[/tex]
We have a system of equations. We can solve by substitution. From the first equation, subtract R from both sides:
[tex]T=25-R[/tex]
Substitute this into the second equation:
[tex](25-R)-8=2(R-8)[/tex]
On the left, subtract. On the right, distribute:
[tex]17-R=2R-16[/tex]
Add 16 to both sides. The right side cancels:
[tex]33-R=2R[/tex]
Add R to both sides. The left cancels:
[tex]33=3R[/tex]
Divide both sides by 3:
[tex]R=11[/tex]
So, Ruby is currently 11 years old.
So, Tanya is currently 25-11 or 14 years old.
Check:
8 years ago, Ruby was 11-8 or 3 years old.
8 years ago, Tanya is 14-8 or 6 years old.
Tanya's age of 6 is 2 times Ruby's age of 3 so our answer is correct.
