One cannot take their driving test.
One can take one's driving test.
( Moon Girl Technologies horrendous beanbag, Tue 12 May 2009, 0:44, archived)

Yes. I'll concede the hastily typed grammar point there, your highness.
I'll leave you to carry on with the mathematics problem though.
( mns 2️⃣2️⃣9️⃣0️⃣7️⃣, Tue 12 May 2009, 0:46, archived)

The mathematics is very simple.
If you had taken your test a year ago, and she had taken it in the last 6 months (for instance), what you just said would still hold.
( Moon Girl Technologies horrendous beanbag, Tue 12 May 2009, 0:49, archived)

But she is 2 years old. I already said that up there^ when I said "I'll leave you to do the maths there"
The mathematics is even simpler in this case. I'll simplify it down into days for you though...

I passed my test 6,510 days ago, when I was 6,318 days old.
The earliest my daughter could take her test is on her 17th birthday which would make her 6,209 days old.

6,510 - 6,209 = 301 days difference.
( mns 2️⃣2️⃣9️⃣0️⃣7️⃣, Tue 12 May 2009, 0:56, archived)

I would dispute that your version is simpler.
Especially since you didn't mention when you passed your test.
( Moon Girl Technologies horrendous beanbag, Tue 12 May 2009, 0:58, archived)