(10а-6b+5c-4d)-(9a-2b-4c+2d)

Помогите пожалуйста очень надо от этого зависит моя оценка в четверти!

Надо решить задачу: 1-Смешали 20 кг воды при 90С и 150 кг воды при 23С. 15% тепла отданного горячей водой пошло на нагревание окружающей среды.Определить конечную температуру воды.

Сочинение на тему Друг познаётся в беде

Напиши короткий рассказ на тему "Почему безделье ничем не пахнет."

проверить правильность построения прредложений. What city is depicted in one of the first card? (Babylon) Who first to describe a polar equi-azimuthal projection of the celestial sphere? (Biruni) Who discovered the New World? (Columbus) Who completed the first circumnavigation? (Elcano) Who wrote the book which called history? (Herodotus) Whom ancient Greeks called the founder of geography? (Homer) Who from Arab scientists created one of the most accurate maps? (Idrisi) Works of Homer (Iliad) Who started the first circumnavigation? (Magellan) How called the city in which lived Thales? (Miletus) Who first to propose a spherical world? (Pythagoras) How many islands depicted on the map of Babylon? (Seven) Who first determine the size of the land and the length of one degree of the meridian? (Eratosthenes) The only ship of the fleet, returned to Spain from circumnavigation. (Victoria)