Because the three are in a straight line, the distance from Xiaogang's home to the school is: the distance from Xiaogang's home to Teacher Wang's home+the distance from Teacher Wang's home to the school, that is, (3.5+0.5)=4 kilometers.

(2) Yes

It takes x hours for Xiao Gang to meet Mr. Wang.

According to the meaning: 15X+5X=3.5.

Solution, X=7/40

After meeting Xiaogang, Mr. Wang will go to school with Xiaogang. The time that Mr. Wang needs from home to school is:

Divide 0.5 by 15 to get 1/30.

So, what Teacher Wang learned when he took Xiaogang to school was * * *:

2*7/40+ 1/30=23/60

That's 23/60 hours, that's 23 minutes.

So if you leave at 7 o'clock, you can get to school at 7: 23.