80 * 3+80 *(t-3+3)= 80 * 3+ 1 10 *(t-3-3)

80t= 1 10t-660

30t=660

t=22

Adhere to the completion within the specified time, the first plan is 240, and the second plan is 330. The distance difference between the two schemes (which can't stop moving within the specified time) is 570m, and the speed difference is 1 10-80=30, so it takes 570/30= 19 minutes, and the specified time is 19+3=22.