445 Выполните действия: a) 3 1/5 * 4 5/21; б) 21 1/5 * 3 4/5; в) 1 1/3 * 3 4/4; г) 3 2/6 * 11 3/11; д) (1 1/5 + 1/20) * 4 5/5; е) (3 1/3 - 1/4) * 12.

a) 3 1/5 * 4 5/21 = 16/5 * 89/21 = 1424/105 = 13 59/105 б) 21 1/5 * 3 4/5 = 106/5 * 19/5 = 2014/25 = 80 14/25 в) 1 1/3 * 3 4/4 = 4/3 * 16/4 = 4/3 * 4 = 16/3 = 5 1/3 г) 3 2/6 * 11 3/11 = 20/6 * 124/11 = 10/3 * 124/11 = 1240/33 = 37 19/33 д) (1 1/5 + 1/20) * 4 5/5 = (6/5 + 1/20) * 9/1 = (24/20 + 1/20) * 9 = 25/20 * 9 = 5/4 * 9 = 45/4 = 11 1/4 е) (3 1/3 - 1/4) * 12 = (10/3 - 1/4) * 12 = (40/12 - 3/12) * 12 = 37/12 * 12 = 37