[tex]-2(1-x) \leq 2x-7\\-2+2x \leq 2x-7\\-2 \leq -7\\\sf There~are~no~solutions~to~this~inequality[/tex]
There are no solutions because the last, final inequality is false.
[tex]\sf Number ~of ~20~dollar~bills = n\\20n \leq 100\\n = 5[/tex]
You can only take a maximum of 5 twenty dollar bills in one transaction.