7 mu, 2 mu

2、

A: y 1=5x.

B: y2=kx+b

The points (1, 7) and (5, 23) are replaced.

7=k+b

23=5k+b

The solution is k=4 and b=3.

That is y2=4x+3.

When 5x=4x+3

That is, when x=3

y 1=y2

A: After 3 hours, the irrigated acres of Team A are equal to those of Team B..