"How long did the strike last?"
Translation:Hoelang duurde de staking?
If you wanted to just say: 'How long does the strike last?', it'd be: Hoelang duurt de staking?. You don't need laatste as duren already means 'to take'/'to last' (in time). 'How long did the strike last?' can only be: Hoelang duurde de staking? (Note in the perfect tense -te goes on words ending in the consonants in "soft ketchup", -de goes on all other)