How many questions does she still need to complete

If Anna completed 40% problems of 30 questions then, it means anna solved ;
30.40/100 = 12 questions (because 40% also means 40/100)

She needs to complete 30-12 = *18* questions more to finish them all.

You can find it finding 10% first and then multiply it by 6 to know how many questions she needs to complete (because if she finished 40/100, then it still has 60/100 --> *100/100 - 40/100 = 60/100* .

like; 30.10/100 = 3
left = 3.6 =18

Hope it helps!
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