we know that
[tex]1\ tens=10 \\1\ hundred=100[/tex]
so
1) the expression [tex]17\ tens[/tex] is equal in numbers to
[tex]17\ tens=17*10=170[/tex]
2) the expression [tex]1\ hundred\ 7\ tens[/tex] is equal in numbers to
[tex]1\ hundred\ 7\ tens=1*100+7*10=100+70=170[/tex]
therefore
[tex]17\ tens[/tex] and [tex]1\ hundred\ 7\ tens[/tex] have the same value
