Answer:
Adam is 9 years old.
Step-by-step explanation:
Let d and c represent Adam's and Alicia's ages.
d = c - 15, and
c + 6 = 2(d + 6)
Rearrange d = c - 15 as c = d + 15, and then substitute d + 15 for c in the second equation. We obtain:
d + 15 + 6 = 2(d + 6), or
d + 21 = 2d + 12
Combining like terms, we get 21 = d + 12, or 9 = d.
If d = 9 then c = d + 15, or c = 9 + 15, or c = 24.
Adam is 9 years old.
