(7/9-1/6):2/9*21/22=

(7/9-1/6):2/9*21/22= 2 5/8.1) 7/ 9 - 1/ 6 = 7·2 /9·2 - 1·3 /6·3 = 14/ 18 - 3 /18 = 14 - 3 /18 = 11 /18.2) 11 /18 ÷ 2/ 9 = 11 /18 × 9 /2 = 11·9 /18·2 = 99 /36 = 11·9 /4·9 = 11/ 4 .3) 11/ 4 × 21 /22 = 11·21/ 4·22 = 231 /88 = 21·11/ 8·11 = 21 /8 = 5 + 2·8/ 8 = 2 5 /8 .