Answer
$\{d\ |\ d\leq-7\}$
Work Step by Step
Solve the inequality.
$7-3d\geq28\longrightarrow$ subtract 7 from each side
$7-3d-7\geq28-7\longrightarrow$ subtract
$-3d\geq21\longrightarrow$ divide each side by -3; flip the inequality
$-3d\div-3\leq21\div-3\longrightarrow$ divide
$d\leq-7$
The solution is written in the criteria area of the set-builder notation.
