（5分之2+10分之3）*60= 60 x 2/5 + 60 x 3/10 = 24 + 18 = 42 11分之5除以8+11分之6*8分之1 (简算)= 5/11 x 1/8 + 6/11 +1/8= 1 /8 x ( 5/11 + 6/11)= 1/ 8 x 1 = 1/8
