Answer the question in the picture?

Can someone me out here number 4 plz

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?

The bottom of a slide at the playground is 6 feet from the base of the play set. the length of the slide is 10 feet. how tall is the slide. 11.66 feet 10 feet 6 feet 8 feet