اليوم عيد ميلادي وأنا أ ضعف العمر الذي كنت عليه قبل سبع سنوات. ما هو عمري؟ 

(Note: The original English question seems to have an error, stating "three times" in the beginning but using "أ ضعف" (double) in the direct translation. The Arabaic answer here directly translates the English sentence, but the English sentence does not seem to correlate internally.) 

If you meant "ثلاث مرات" (three times), the sentence should be like this in English: 
"Today is my birthday and I am three times as old as I was six years ago. What is my age?" 

If you meant "أ ضعف" (double), the sentence should be like this in English:
"Today is my birthday and I am twice as old as I was seven years ago. What is my age?"
نعلم أن عمري مقسومًا على ثلاثة يساوي عمري ناقص ستة وبالتالي X/3 = X-6 حيث X = عمري
这意味着 X = 3X - 18 لأننا يمكن أن نضرب الجانبين بثلاثة
هذا يعني أيضا أن -2X = -18 لأننا يمكن أن نطرح 3X من الجانب الأيمن.
لذلك X = 9 لأن - 18 / -2 = 9
#### 9