math
posted by chrissy on .
bill is 2 years older than ted. in 5 years, 5 times ted's age will be 4 times bill's age. how old is ted?

bill is 2 years older than ted. in 5 years, 5 times ted's age will be 4 times bill's age. how old is ted?
B = T + 2
4(B + 2) = 5(T + 2)
Can you take it from here. 
let x=Bill's age, y=Ted's age
Bill is two years older than Ted. This gives the first equation:
y=x2
In 5 years, their ages will be:
Bill=(x+5), Ted=(y+5)
and...
4*Bill's age=5*Ted's age
4*(x+5)=5*(y+5)
Use the first equation to substitute for y in the second equation. Then, you will only have x's. Solve for x. Plug the solved value for x into the first equation to easily find y. 
Bill is 2 years older than ted
(1) b = t + 2
where b = bill's age TODAY and t = ted's age TODAY
In 5 years 5 times ted's age will be 4 times bill's age:
(2) 5(t+5) = 4(b+5)
Put equation (1) into (2) for b.
5(t+5) = 4(t+2+5) ==> 5t+25 = 4t+28
solve for t to get t = 3
So ted is 3 and bill is 5 years old.