A rectangle's length is 5 more than 3 times its width. If the perimeter is 58, what is the length of the rectangle?

Let the width be $w$, so the length is $3w+5$. The perimeter is $2(w+3w+5)=58$, so $4w+5=29$, $4w=24$, and $w=6$. The length is $3(6)+5=23$, choice H. Check: $2(6+23)=58$. Choice F ($6$) is the width, not the length. Choice G ($18$) is $3w$, leaving out the extra $5$. Choice J ($29$) is half the perimeter, which is the sum of the length and the width, not the length alone. Reread the question to confirm which dimension is requested.