Answer:
The man traveled 20km by train.
Step-by-step explanation:
If x is the distance he traveled by train, you can write this equation to represent the situation:
[tex]10+x+2x=70[/tex]
Then, you can simply solve for x:
[tex]10+3x=70\\3x=60\\x=20[/tex]
The man traveled 20km by train.
[tex]10+(20)+2(20)=70\\10+20+40=70\\70=70[/tex]