(4/5+1/6)*(23, 2/3- 15, 5/9) * 45/58 -1/2=

=29/30*(71/3-140/9)*45/58-1/2=29/30*73/9*45/58-1/2=73/12-1/2=67/12=5 7/12

(4/5+1/6)*(23, 2/3- 15, 5/9) * 45/58 -1/2=29.30* 8  4/9* 45/85 -1/2=29/30*76/9*45/85-1/2=73/12-1/2=5 7/12