(2,25-5,25)+(2/9 - 5/18)

2.25=2 1/4=9/45,25=5 1/4=21/49/4-21/4= -12/4= -32/9-5/18=4/18-5/18= -1/18-3+(-1/18)= -3-1/18= -3 1/18