Answer
$p = -4/3$
or
$p = 5$
Work Step by Step
$3p^2-11p-20$
The coefficient 3 multiplies with -20 to get (-60)
$-15 * 4 = -60$
$-15 + 4 = -11$
$3p^2 -15p+4p-20$
$3p(p-5)+4(p-5)$
$(3p+4)(p-5)$
$3p+4=0$
$3p=-4$
$p=-4/3$
or
$p-5=0$
$p=5$
Therefore, p equals either $-4/3$ or $5$
