1/4+2/5 2/3+1/4 5/7-1/6 3/4-1/3

1/4+2/5=5/20+8/20=13/20 2/3+1/4=8/12+3/12=11/12 5/7-1/6=30/42-7/42=23/42 3/4-1/3=9/12-4/12=5/12

[latex] \frac{1}{4} + \frac{2}{5} = \frac{5}{20} + \frac{8}{20} = \frac{13}{20} = 0,65 [/latex] [latex] \frac{2}{3} + \frac{1}{4} = \frac{8}{12} + \frac{3}{12} = \frac{11}{12} [/latex] [latex] \frac{5}{7} - \frac{1}{6} = \frac{30}{42} - \frac{7}{42} = \frac{23}{42} [/latex] [latex] \frac{3}{4} - \frac{1}{3} = \frac{9}{12} - \frac{4}{12} = \frac{5}{12} [/latex]