5/12 : 2/5 - 1/3 : 2/5 + 7/12 : 2/5
= 5/12 x 5/2 - 1/3 x 5/2 + 7/12 x 5/2
= (5/12 - 1/3 + 7/12) x 5/2
= (5/12 + 7/12 - 1/3) x 5/2
= (1 - 1/3) x 5/2
= (3/3 - 1/3) x 5/2
= 2/3 x 5/2
= 5/3
\(\frac{5}{12}\):\(\frac{2}{5}\)-\(\frac{1}{3}\): \(\frac{2}{5}\)+ \(\frac{7}{12}\):\(\frac{2}{5}\)= ( \(\frac{5}{12}\)-\(\frac{1}{3}\)+\(\frac{7}{12}\)) : \(\frac{2}{5}\)
= ( \(\frac{1}{12}\)+ \(\frac{7}{12}\)) : \(\frac{2}{5}\)
= \(\frac{8}{12}\): \(\frac{2}{5}\)
=\(\frac{5}{3}\)