Answer :

naǫ
[tex]10|7-x| \hbox{ when } x=5 \\ 10|7-5|=10|2|=10 \times 2=\boxed{20} \Leftarrow \hbox{answer B}[/tex]
10|7 - x|
10|7 - 5|
10|2|
10(2)
20

B.20