Julio can finish the job in 6 hours, so his rate is $\frac{1}{6}$ of the job per hour.

Carlos can finish the job in 8 hours, so his rate is $\frac{1}{8}$ of the job per hour.

Combined rate:

$\frac{1}{6} + \frac{1}{8} = \frac{4}{24} + \frac{3}{24} = \frac{7}{24} \text{ per hour}$

In 2 hours they complete:

$2 \times \frac{7}{24} = \frac{7}{12} \text{ of the job}$