<img src="/close/store/examRes/%7B881BFD6F-A403-4DA4-A5FA-C137FFF800FA%7D/%D0%B2%D0%BE%D0%BF%D1%80%D0%BE%D1%81%2025.3.png" /> Iw = (H1 + H2)(l1 + l2), Iw = H(l1 + l2), Iw = H1/l1 + H2/l2, Iw = H1l1 + H2l2