Answer
$\color{blue}{9k^2-30km+25m^2}$
Work Step by Step
RECALL:
$(a-b)^2=a^2-2ab+b^2$
Use the formula above with $a=3k$ and $b=5m$ to obtain:
$=(3k)^2-2(3k)(5m) + (5m)^2
\\=\color{blue}{9k^2-30km+25m^2}$
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