Answer:7z^3+6z^2-27z+22Step-by-step explanation:The given question is of subtraction:So,(7z^3+42z^2-15z+1)- (36z^2+12z-21)β=7z^3+42z^2-15z+1-36z^2-12z+21Combining alike terms to simplify=β7z^3+42z^2-36z^2-15z-12z+1+21=7z^3+6z^2-27z+22So the answer in simplified form is:7z^3+6z^2-27z+22 ..