Chapter 2 - Section 2.1 - The Distance and Midpoint Formulas - 2.1 Assess Your Understanding - Page 157: 74

$x=-\dfrac{5}{3}$ or $x=4$

Factor the trinomial to obtain: $$(3x+5)(x-4)=0$$ Use the Zero-Product Property by equating each factor to zero, then solve each equation to obtain: \begin{align*} 3x+5&=0 &\text{pr}& &x-4=0\\ 3x&=-5 &\text{or}& &x=4\\ x&=-\dfrac{5}{3} &\text{or}& &x=4 \end{align*}