Решить дроби. И под №3 уравнение
= 15/7 * 28/9 = 20/3 = 6 2/3 = 31/7 * 7/1 - 11/6 * 3 = 31 - 33/6 = 31 - 5 3/6 = 25 1/2 (8/9)у = 36/5 у = 36/5 * 9/8 = 81/10 = 8 1/10 1/3 * 81/10 + 5/9 * 81/10 = 81/10 * 8/9 = 72/10 = 7 1/5