12*4/9*57/8*3/2 17/15+17/15*16 120*119/2 (9/1*85/3)*18*51

12*4/9*57/8*3/2
=12*(4/8*2)*(57*3/9)
=12*4*(19*3*3/9)
=48*19
=48*(20-1)
=48*20-48*1
=960-48
=912
17/15+17/15*16
=(17/15)*(1+16)
=(17/16)*17
=16
120*119/2
=(119+1)*119/2
=119*119/2+1*119/2
=2+119/2
=2又119分之2
(9/1*85/3)*18*51
=(9/18)*(85/3*51)
=2*(17*5/3*17*3)
=2*(5/9)
=5/18
=3又5分之3

12*4/9*57/8*3/2
=12*(4/8*2)*(57*3/9)
=12*4*(19*3*3/9)
=48*19
=48*(20-1)
=48*20-48*1
=960-48
=912