1)((b²xy/9a²)÷(7xy/12a⁵))·(28a⁴/3b²)=/(b²xy·12a⁵·28a⁴)/(9a²·7xy·3b²)=
=(336·a⁵⁺⁴·b²xy)/(189·a²·b²·xy)=сокращаем=
=(16/9)·a⁷
2)(3mx²y/2a²b²)·(3abc/8p²q²)÷(9a²b²c³/28xpq)=
=(3mx²y·3abc·28xpq)/(2a²b²·8p²q²·9a²b²c³)=
=(252abcpqmx²⁺¹y)/(144a²⁺²b²⁺²c³p²q²)=сокращаем=
=(7mx³y)/(4a³b³c²pq)