[tex] \frac{5}{12} a + 2.5 = 4 \frac{2}{3} \\ \frac{5}{12} a = 4 \frac{2}{3} - 2 \frac{5}{10} \\ \frac{5}{12} a = \frac{14}{3} - \frac{25}{10} \\ \frac{5}{12} a = \frac{65}{30} | \times \frac{12}{5} \\ a = \frac{78}{15} = 5 \frac{3}{15} [/tex]
