(4p-5q)^2 + 40pq

$(4p - 5q)^2 + 40pq = (4p)^2 - 2 \cdot 4p \cdot 5q + (5q)^2 + 40pq = 16p^2 - 40pq + 25q^2 + 40pq = \textbf{16p^2 + 25q^2}$