a)
[tex] \frac{5}{4} - \frac{7}{12} = \frac{15}{12} - \frac{7}{12} = \frac{8}{12} = \frac{2}{3} [/tex]
b)
[tex] \frac{8}{3} \div \frac{16}{5} - \frac{1}{9} = \frac{8}{3} \times \frac{5}{16} - \frac{1}{9} = \frac{1}{3} \times \frac{5}{2} - \frac{1}{9} [/tex]
[tex] \frac{1}{3} \times \frac{5}{2} - \frac{1}{9} = \frac{5}{6} - \frac{1}{9} = \frac{15}{18} - \frac{2}{18} = \frac{13}{18} [/tex]
c)
3/10+20/9:8/3
3/10+20/9×3/8
3/10+5/3×1/2
3/10+5/6
9/30+25/30=34/30=17/15
d)11/6-4/45:8/6
11/6-4/45×6/8
11/6-1/15×2/2
11/6-2/30
55/30-2/30
53/30
e)63/50:9/2+13/15
63/50×2/9+13/15
7/25×1/1+13/15
7/25+13/15
42/150+130/150
=172/150
=86/75
f)49/20:14/5+5/18
49/20×5/14
7/4×1/2+5/18
7/8+5/18
63/72+20/72
=83/72
