Question

-2/5 + 7/21

Answer 1

\(-\dfrac{2}{5}+\dfrac{7}{21}\\ =\dfrac{-2\times21+7\times5}{105}=\dfrac{-42+35}{105}=\dfrac{-7}{105}=-\dfrac{1}{15}\)

Answer 2

-2/5 + 7/21 = (-22 + 35)/105

= 13/105

Answer 3

\(-\dfrac{2}{5}+\dfrac{1}{3}=-\dfrac{6}{15}+\dfrac{5}{15}=-\dfrac{1}{15}\)

Answer 4

\(\dfrac{-2}{5}+\dfrac{7}{21}=\dfrac{-42}{105}+\dfrac{35}{105}=\dfrac{-7}{105}=\dfrac{-1}{15}\)

Answer 5