Does anyone know what residuals is? Please Help

Brainliest ! which of the coordinates are not of th vertices of the feasible region for the system of inequalities y≤4,,x≤5,x+y> 6 a(2,4) b(0,6) c(5,4) d(5,1)

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?

I’ve been trying all day to figure this puzzle out. i need the work for it aswell. it is a factoring polynomials tarsia. the image is below.