$(14023 xx 9 + 38942 xx 8 + 13991 xx 7) xx (15 x 6 - 90)\\=(14023 xx 9 + 38942 xx 8 + 13991 xx 7) xx(90-90)\\(14023 xx 9 + 38942 xx 8 + 13991 xx 7) xx0\\=0$
(14023 x 9 + 38942 x 8 + 13991 x 7) x (15 x 6 - 90)
= (14023 x 9 + 38942 x 8 + 13991 x 7) x (90 - 90)
=(14023 x 9 + 38942 x 8 + 13991 x 7) x 0 = 0