Question

Выполните сложение: - 2/3+1/18
Выполните вычитание : 3/7+(- 7/9

Answer 1

$- cfrac{2}{3}+ cfrac{1}{18} = - cfrac{12}{18}+ cfrac{1}{18} = cfrac{1-12}{18} =- cfrac{11}{18} \\ cfrac{3}{7} +(- cfrac{7}{9} )= cfrac{27}{63} - cfrac{49}{63}= cfrac{27-49}{63} =- cfrac{22}{63}$