1)1/2+2/4= 2)3/4-5/8= 3)2/3-3/5= 4)5/12+4/9=

1) $\frac{1}{2} + \frac{2}{4} = \frac{1*2}{2*2}+\frac{2}{4} =\frac{2}{4}+\frac{2}{4}=1$
2) $\frac{3}{4}-\frac{5}{8} =\frac{3*2}{4*2}-\frac{5}{8}=\frac{6}{8}-\frac{5}{8} =\frac{1}{8}$
3) $\frac{2}{3}-\frac{3}{5} = \frac{2*5}{3*5}- \frac{3*3}{5*3} =\frac{10}{15}- \frac{9}{15} =\frac{1}{15}$
4) $\frac{5}{12}+ \frac{4}{9} = \frac{5*3}{12*3}+ \frac{4*4}{9*4} =\frac{15}{36}+ \frac{16}{36} = \frac{31}{36}$