تساوی ها را کامل کنید.
\(\begin{array}{*{20}{l}}{ + 15 = 15}&{}&{ + 20 = }\\{}&{}&{}\\{ - ( + 10) = }&{}&{ - ( - 4) = }\\{}&{}&{}\\{ - ( - ( + 7)) = }&{}&{ - ( - 10) = }\\{}&{}&{}\\{ + ( - 7) = }&{}&{ + ( - 4) = }\end{array}\)
\(\begin{array}{*{20}{l}}{ + 15 = 15}&{}&{ + 20 = 20}\\{}&{}&{}\\{ - ( + 10) = - 10}&{}&{ - ( - 4) = + 4}\\{}&{}&{}\\{ - ( - ( + 7)) = + 7}&{}&{ - ( - 10) = + 10}\\{}&{}&{}\\{ + ( - 7) = - 7}&{}&{ + ( - 4) = - 4}\end{array}\)