ANSWER:
STEP-BY-STEP EXPLANATION:
We must approximate each addition or subtraction, estimating if it is close to 0, 1/2 or 1.
We operate in each case:
[tex]\begin{gathered} \frac{1}{8}+\frac{2}{5}=\frac{1\cdot5+2\cdot8}{8\cdot5}=\frac{5+16}{40}=\frac{21}{40}=0.525\approx\frac{1}{2} \\ \\ \frac{13}{14}-\frac{1}{10}=\frac{13\cdot10-1\cdot14}{14\cdot10}=\frac{130-14}{140}=\frac{116}{140}=0.82\approx1 \\ \\ \frac{1}{12}+\frac{1}{20}=\frac{20+12}{12\cdot20}=\frac{32}{240}=0.13\approx0 \end{gathered}[/tex]
