## Algebra 1

$1\leq r \lt4$
$-4\leq r-5\lt-1\longrightarrow$ add 5 to each of the 3 parts $-4+5\leq r-5+5\lt-1+5\longrightarrow$ add $1\leq r \lt4$ The endpoint is a solid circle at 1 to indicate that it is included in the solution, and there is an open circle at 4 to indicate it is not included in the solution.