[tex] \frac{7}{12} - \frac{8}{15} + \frac{17}{20} \\ \\ \frac{7 \times 5}{12 \times 5} - \frac{8 \times 4}{15 \times 4} + \frac {17 \times 3}{20 \times 3} \\ \\ \frac{35}{60} - \frac{32}{60} + \frac{51}{60} \\ \\ \frac{35 -32 + 51}{60} \\ \\ \frac{54}{60} \\ \\ \frac{9}{10} [/tex]
R : 9/10
