Answer: Michael is 39 years old.
Explanation:
Let l stand for Luis, s stand for Santiago, and m stand for Michael.
l = s - 6
m = 3s
s + (s-6) + 3s = 59
s + s - 6 + 3s = 59
5s - 6 = 59
+6 +6
5s = 65
/5 /5
s = 13
Now plug s into the equation that represents Michael:
m = 3s
m = 3(13)
m = 39
Michael is 39 years old.