Calculus with Applications (10th Edition)

$-\displaystyle \frac{7}{8}$
The aim is, step by step, to isolate $r$ on one side of the equation. ...Multiply out the parentheses on the left side: $-5(r+1)$ $3r+2-5r-5=6r+4$ ...add/subtract like terms on the left side $-2r-3=6r+4$ ...Adding 3 to both sides removes free numbers from the left side ...Subtracting 6r from both sides removes terms containing r from the right side, $-2r-3=6r+4\qquad .../+3-6r$ $-2r-6r=4+3\qquad ...$simplify $-8r=7$ ...Dividing both sides with $(-8)$ isolates $r$ on the left side. $-8k=7 \qquad$...$/\div(-8)$ $r= -\displaystyle \frac{7}{8}$