$d=7$ or $d=-3$
Work Step by Step
$5d^2-20d=105$ $5d^2-20d-105=0$ $5d^2+15d-35d-105=0$ $5d(d+3)-35(d+3)=0$ $(5d-35)(d+3)=0$ $5(d-7)(d+3)=0$ $d-7=0$ or $d+3=0$ $d=7$ or $d=-3$
You can help us out by revising, improving and updating this answer.Update this answer
After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.