a)
[tex] \frac{1}{5} \times \frac{7}{8} = \frac{1 \times 7}{5 \times 8} = \frac{7}{40} = \frac{7}{20} [/tex]
b)
[tex] \frac{3}{7} \times \frac{5}{8} = \frac{3 \times 5}{7 \times 8} = \frac{15}{56} = \frac{5}{7} [/tex]
[tex] \frac{2}{5} \times \frac{13}{7} = \frac{2 \times 13}{5 \times 7} = \frac{26}{35} = \frac{13}{7} [/tex]
c)
[tex] \frac{3}{4} \times \frac{17}{19} = \frac{3 \times 17}{4 \times 19} = \frac{51}{76} = \frac{17}{38} [/tex]
[tex] \frac{1}{4} \times \frac{7}{6} = \frac{1 \times 7}{4 \times 6} = \frac{7}{24} = \frac{7}{4} [/tex]
d)
[tex] \frac{5}{3} \times \frac{13}{4} = \frac{5 \times 13}{3 \times 4} = \frac{65}{12} = \frac{5 \times 12 + 5}{12} = 5 \frac{2}{12} [/tex]
[tex] \frac{2}{9} \times \frac{17}{9} = \frac{2 \times 17}{9 \times 9} = \frac{34}{81} = \frac{17}{27} [/tex]