[7/8+4/9]除1/72 1/8除1/5-5/8x10/11 7/15除14除2/3 3/4除12x16/21+3/14 7/8除[2/5+1/20]x4/21

[7/8+4/9] ÷ 1/72 = [7/8+4/9] * 72 = 7/8* 72 +4/9* 72 = 63+32 = 951/8÷1/5-5/8x10/11 = 1/8 * 5 - 5/8x10/11= 5/8 - 1/44 =（55-2)/88 = 53/887/15÷14÷2/3 = 7/15 * 1/14* 3/2 = 1/5 * 1/2 *1/2 = 1/203/4÷1...