How many question are in a test if you show 20% completed and you only answer 16 questions

To solve, create the proportion

16 20
_ = _
? 100

Next cross multiply and divide

16*100=1600

1600/20=80

80 questions

Cdoes not have two variables

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.