Help please but also explain I don’t understand

Iwant to know what 3g+5h+4g-2h is my teacher is too selfish to tell us

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?

Jahdzia wears her winter coat when the temperature is colder than -4 degrees celsius. write an inequality that is true only for temperatures (t) at which jahdzia wears her winter coat.