А) (-3,25+(-1 3/4)) + (-1 2/3+(-1 4/9))= (-3 1/4+(-1 3/4)) + (-1 2/3+(-1 4/9) = -(3 1/4+1 3/4) + (-(1 2/3+1 4/9)) = -4 4/4 + (-(5/3+13/9) = -5+(-(15+13)/9) = -5 - 28/9 = -5 - 3 1/9 = -8 1/9
Б) (-2/3+(-2/15)) + (-1,85+(-1,35)) = (-(10+2)/15) + (-1 17/20+(-1 7/20) = -12/15+(-37/20+(-27/20) = -4/5+(-(37+27)/20) = -4/5-67/20 = -(16+67)/20 = -83/20 = -4 3/20