Billy bob spend $15 for 20 pokemon cards, how much will he spend for 75 pokemon cards?

$56.25

$15 ÷ 20 cards = $.75 per card

$.75 × 75 cards = $56.25

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.