Only one correct answer

Given this information, which expression must represent the value of b?

On average a herd of elephants travels 10 miles in 12 hours you can use that information to answer different questions drag each expression to show which is answers

He ! a group of farmers planned to clean 80 acres of wheat per day to finish the work on schedule. right before the work started, they received a new piece of machinery that them clean 10 more acres per day than originally planned. as a result of increased productivity in the last day before the deadline they only had to clean 30 acres. how many acres of wheat did the group of farmers have to clean?