Sally will be 12 in 4 years, because bob is 28 and sally is 8; then in two years bob will be 30, while sally is 10 making bob 3 times her age!
The answer would be 10. You would get it by multiplying 50 by 0.2. Hope I helped!
X= -b / (2a)
Then once you find x plug it in to find y