Answer:
Ralph's current age is 18.
Explanation:
Let r and s represent the current ages of Ralph and Sara respectively. Our task here is to determine r, Ralph's age now.
If Ralph is 3 times as old as Sara now, then r = 3s.
Six years from now, Ralph's age will be r + 6 and Sara's will be s + 6. Ralph will be only twice as old as Sara will be then. This can be represented algebraically as
r + 6 = 2(s + 6).
We now have the following system of linear equations to solve:
r + 6 = 2s + 12, or r - 2s = 6, and r = 3s (found earlier, see above).
r - 2s = 6
r = 3s
Substituting 3s for r in r - 2s = 6, we get 3s = 2s + 6, or s = 6. Sara is 6 years old now, meaning that Ralph is 3(6 years), or 18 years old.
Ralph's current age is 18.