a= 9/8+35/40-27/72+7/8
numitorul comun= 5×8×9 = 360
9/8 amplificam cu 45 = 9×45/360= 405/360
35/40 amplificam cu 9 = 9×35/360 = 315/360
27/72 amplificam cu 5 = 5×27/360 = 135/360
7/8 amplificam cu 45 = 7×45/360 = 315/360
a = (405+315-135+315)/360
a = 900/360 (simplificam cu 100)
a = 90/36 ( cu 9)
a= 10/4 ( cu 2)
a= 5/2