Bookstore sells book in excellent condition for $2.50 and in fair condition for $0.50 . write an expression for cost of buying x excellent condition paperbacks and fair paperbacks

X = excellent condition books
y = fair condition books

2.50x + 0.50y <== ur expression

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.