Answer: 4
Step-by-step explanation:
Let P represent Pete's age today. Â Let C represent Claire's age today.
2 years ago: P - 2 = 3(C - 2)  ⇒  P - 2 = 3C - 6  ⇒  P = 3C - 4
4 years ago: P - 4 = 4(C - 4)  ⇒  P - 4 = 4C - 16  ⇒  P = 4C - 12
Use substitution to solve the system above:
3C - 4 = 4C - 12
   - 4 = C - 12
    8 = C
Plug in the C-value above into one of the equations to solve for P:
P = 3C - 4
 = 3(8) - 4
 = 24 - 4
 = 20
So, Pete is 20 yrs old today and Claire is 8 years old today
When will Pete be twice as old as Claire?
20 + x = 2(8 + x)
20 + x = 16 + 2x
20 Â Â Â = 16 + x
4 Â Â Â Â Â = x
Their ages will have a 2:1 ratio in 4 years. Â