Answer
$t=10$
Work Step by Step
$\displaystyle \frac{1}{3-t}+\frac{4}{3+t}+\frac{15}{9-t^{2}}=0$
We multiply by $(3+t)(3-t)$:
$(3+t)+4(3-t)+15=0$
Then we distribute and simplify:
$3+t+12-4t+15=0$
$-3t+30=0$
$-3t=-30$
And solve for $t$:
$t=10$