Вычислите
3/5:9/10-3/5*8/9

3/5 : 9/10 - 3/5 * 8/9 = 3/5 * 10/9 - 3/5 * 8/9 = 3/5 * (10/9 - 8/9) = 3/5 * 2/9 = 1/5 * 2/3 = 2/15