7. One morning, DuoDuo left for school at a little past 7 o'clock, at which time the angle between the hour and minute hands was $100^{\circ}$. That afternoon, DuoDuo returned home at a little past 5 o'clock, at which time the angle between the hour and minute hands was $70^{\circ}$. Given that DuoDuo was out of the house for more than 10 hours that day, the time DuoDuo left home was 7: $\qquad$ minutes.
$20$