#### Answer

11 roses

#### Work Step by Step

Substitute for c and solve for r.
$50=3r+15$ subtract 15 from both sides
$50-15=3r+15-15$ simplify
$35=3r$ divide both sides by 3
$35\div3=3r\div3$
$11\frac{2}{3}=r$
You cannot buy part of a rose, so the correct answer is 11.