\(A = 8{2 \over 7} - \left( {3{4 \over 9} + 4{2 \over 7}} \right)\)

\( = 8{2 \over 7} -3{4 \over 9} - 4{2 \over 7}\)

\(=8{2 \over 7}- 4{2 \over 7}-3{4 \over 9}\)

\(=4-3{4 \over 9}\)

\(=3\frac{9}{9}-3{4 \over 9}\)

\(=\frac{5}{9}\)

\(B = \left( {10{2 \over 9} + 2{3 \over 5}} \right) - 6{2 \over 9}\)

\( = 10{2 \over 9} - 6{2 \over 9} + 2{3 \over 5}\)

\(= 4 + 2{3 \over 5} \)

\(= 6{3 \over 5}\)