Đáp án:
\(\begin{array}{l}
a)\dfrac{{73}}{{72}}\\
b)\dfrac{{17}}{4}\\
c) - \dfrac{3}{4}\\
d)\dfrac{1}{{30}}
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a)\dfrac{7}{{18}} + \dfrac{5}{8} = \dfrac{{7.8 + 5.18}}{{18.8}} = \dfrac{{56 + 90}}{{144}} = \dfrac{{73}}{{72}}\\
b)\dfrac{{36}}{{48}} + \dfrac{{105}}{{30}} = \dfrac{3}{4} + \dfrac{7}{2} = \dfrac{{3 + 7.2}}{4} = \dfrac{{17}}{4}\\
c)\dfrac{{24}}{{48}} - \dfrac{{10}}{8} = \dfrac{1}{2} - \dfrac{5}{4} = \dfrac{{2 - 5}}{4} = - \dfrac{3}{4}\\
d)\dfrac{{70}}{{84}} - \dfrac{{56}}{{70}} = \dfrac{5}{6} - \dfrac{4}{5} = \dfrac{{25 - 24}}{{30}} = \dfrac{1}{{30}}
\end{array}\)
