\(\displaystyle {7 \over {10}} = {5 \over {10}} + {2 \over {10}} = {1 \over 2} + {1 \over 5} \)
\(\displaystyle {{10} \over {21}} = {7 \over {21}} + {3 \over {21}} = {1 \over 3} + {1 \over 7} \)
\(\displaystyle {7 \over 8} = {4 \over 8} + {2 \over 8} + {1 \over 8} = {1 \over 2} + {1 \over 4} + {1 \over 8} \)
