23/45 - 12/45 + 21/45 = 32/45
109/250 - (16/250 + 63/250) = 30/250
57/190 - ( 32/190 - 12/190) = 37/190
35/67+(15/67-9/67)= 29/67
(42/56+8/56)-29/56= 21/56
203/300+(190/300-150/300)=163/300
1)32/45
2)30/250
3)37/190
4)41/67
5)21/56
6)243/300
