2/3+4/5; 23/8+13/4: 3-17/9: 31/2+1/3: 1 1/5-3/4;

2/3+4/5=10/15+12/15=22/15=1 7/15
23/8+13/4=23/8+26/8= 49/8= 6 1/8
3-17/9= 27/9-17/9=10/9=1 1/9
31/2+1/3= 93/6+2/6= 95/6= 15 5/6
1 1/5-3/4 = 6/5-3/4= 24/20- 15/20 = 9/20

[tex] \frac{2}{3} + \frac{4}{5} = \frac{2*5+4*3}{15}= \frac{22}{15} =1 \frac{7}{15}

\frac{23}{8} + \frac{13}{4} = \frac{23+13*2}{8} = \frac{49}{8} =6 \frac{1}{8}

3- \frac{17}{9} = \frac{27}{9} - \frac{17}{9} = \frac{10}{9} =1 \frac{1}{9}

\frac{31}{2} + \frac{1}{3} = \frac{31*3+1*2}{6} = \frac{95}{6} = 15 \frac{5}{6}

1 \frac{1}{5} - \frac{3}{4} = \frac{6*4-3*5}{20}= \frac{9}{20} [/tex]