a)
[tex]18 + ( - 21) = 18 - 21 = - 3[/tex]
b)
[tex]2.7 - ( - 6.9) = 2.7 + 6.9 = 9.6[/tex]
c)
[tex] - 8 - \frac{21}{12} = - \frac{96}{12} - \frac{21}{12} = - \frac{117}{12} = - 9 \frac{9}{12} = - 9 \frac{3}{4} [/tex]
d)
[tex] - \frac{481}{7} - ( - 13) = - \frac{481}{7} + \frac{91}{7} = - \frac{390}{7} = - 55 \frac{5}{7} [/tex]
e)
[tex] - 16 + ( - 4) + ( - 10) = 16 - 4 - 10 = 12 - 10 = 2[/tex]
f)
[tex] - 11 \frac{3}{4} - 4 \frac{1}{2} = - 11 \frac{3}{4} - 4 \frac{2}{4} = - 16 \frac{1}{4} [/tex]
