$2\frac{1}{5} + 3\frac{1}{4} - 4\frac{1}{2}=(2+3-4)+(\frac{1}{5}+\frac{1}{4}-\frac{1}{2})=1+(\frac{1}{5}+\frac{1}{4}-\frac{1}{2})=1+\frac{4+5-10}{20}=1-\frac{1}{20}=1-\frac{5}{100}=\frac{95}{100}=0/95$