Working alone ryan can dig a 10ft by 10ft hole in five hours. castel can dig the same hole in six hours how long would it take them to dig the hole if they worked together

Agroup 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?