Найдите значение выражения а)(4/5-11/15)*5/11 б)7/88*(8/21+8/7) в) 3/7*(1/4+7/12)

а) (4/5 - 11/15) * 5/11 = 4/5 * 5/11 - 11/15 * 5/11 = 4/11 - 1/3 = 12/33 - 11/33 = 1/33;б) 7/88 * (8/21 + 8/7) = 7/88 * 8/21 + 7/88 * 8/7 = 1/33 + 1/11 = 1/33 + 3/33 = 4/33;в) 3/7 * (1/4 + 7/12) = 3/7 * 1/4 + 3/7 * 7/12 = 3/28 + 1/4 = 3/28 + 7/28 = 10/28 = 5/14.