(2) Given the abscissa of point B, we need the ordinate of point B. Considering that point B is still on the straight line BD, we can try to find the analytical formula of straight line BD first. Considering that the analytical formula of straight line EF can be found, the coordinates of point C can be found, and then the analytical formula of straight line BD can be found from the coordinates of point C and point D, so that the ordinate of point B can be found.

Let the analytical formula of straight line EF be y = kx+b.

Both point E (1.25,0) and point F (7.25,480) are on the straight line EF.

The analytical formula of straight line EF is y=80x- 100.

Point c is on the straight line EF, and the abscissa of point c is 6.

The ordinate of point C is 80× 6-100 = 380.

The coordinate of point C is (6380).

Let the analytical formula of straight line BD be y a = MX+n.

Point C (6380) and point D (7480) are on the straight line BD.

Therefore, the analytical formula of BD is y A = 100x-220.

Because point B is on the straight line BD, the abscissa of point B is B (4.9), and it is substituted to get B (4.9,270).

Therefore, when troubleshooting in group A, the distance from the starting point is 270 kilometers.

(3) when x=4.9, y = 4.9x80-100 = 292 (km) 292-270 = 22 (km) ∫ 22km < 25km ∴ meet the agreement.