Приведем дроби 1/2 и 1/3 к общему знаменателю 6. Получим 1/2=3/6, 1/3=2/6
3 1/2+1/3=3 3/6 + 2/6=3 5/6
(-3 1/3 + 2 5/6)*(-8 5/9 + 7 2/9)=2/3
1) -(3 2/6 - 2 5/6) = -(2 8/6 - 2 5/6) = - 3/6 = - 1/2,
2) -(8 5/9 - 7 2/9) = - 1 3/9 = - 1 1/3,
3) - 1/2 * (-1 1/3) = 1/2 * 4/3 = 1/1 * 2/3 = 2/3
19-5<12+8
5+9<19-5
12+8=26-6
5+9=19-5