1) 10 1/2- 2/3 2)найдите 2/5 от 25 3 )вычислите 5/7 * 21/25 + 3/5 : 9/11

а) 10 1/2 - 2/3 = 10 3/6 - 4/6 = 9 9/6 - 4/6 = 9 5/6 б) 2/5 * 25 = 25 : 5 * 2 = 10 в) 5/7 * 21/25 + 3/5 : 9/11 = 1 1/3 1) 5/7 * 21/25 = (1*3)/(1*5) = 3/5 2) 3/5 : 9/11 = 3/5 * 11/9 = (1*11)/(5*3) = 11/15 3) 3/5 + 11/15 = 9/15 + 11/15 = 20/15 = 1 5/15 = 1 1/3