Question

Выполните действие: а) 2/9 + 5/15
б) 17/20 - 5/12
в) 11/12 - - (2/3 + 1/4)

Answer 1

(2*5+5*3)/45=25/45=5/9
(17*3-5*5)/60=26/60=13/30
11/12-((2*4+3)/12)=0

Answer 2

$frac{2}{9} + frac{5}{15} = frac{30}{135} + frac{40}{135} = frac{75}{135} = frac{5}{9}$
$frac{17}{20} - frac{5}{12} = frac{51-25}{60} = frac{26}{60} = frac{13}{30}$
$frac{11}{12} - ( frac{2}{3} + frac{1}{4} ) = frac{11}{12} - ( frac{8}{12} + frac{3}{12} ) = frac{11}{12} - frac{11}{12} = 0$