a) \( \displaystyle {1 \over 3} + {3 \over 8} - {7 \over {12}} ={8 \over 24} + {9 \over 24} - {14 \over {24}}\)\( \displaystyle = {{8 + 9 - 14} \over {24}} = {3 \over {24}} = {1 \over 8}\)
b) \( \displaystyle {{ - 3} \over {14}} + {5 \over 8} - {1 \over 2} ={{ - 12} \over {56}} + {35 \over 56} - {28 \over 56} \)\( \displaystyle = {{ - 12 + 35 - 28} \over {56}} = {{ - 5} \over {56}}\)
c) \( \displaystyle {1 \over 4} - {2 \over 3} - {{11} \over {18}} ={9 \over 36} - {24 \over 36} - {{22} \over {36}}\)\( \displaystyle = {{9 - 24 - 22} \over {36}} = {{ - 37} \over {36}}\)
d) \( \displaystyle {1 \over 4} + {5 \over {12}} - {1 \over {13}} - {7 \over 8} \)\( \displaystyle = \dfrac{1}{{4.78}} + \dfrac{{5.26}}{{12.26}} - \dfrac{{1.24}}{{13.24}} - \dfrac{{7.39}}{{8.39}}\)\( \displaystyle = {{1 . 78 + 5 . 26 - 1 . 24 - 7 . 39} \over {312}}\)
\( \displaystyle = {{78 + 130 - 24 - 273} \over {312}} = {{208 - 297} \over {312}} \)\( \displaystyle = {{ - 89} \over {312}}\)
