Answer
$ a=1$
$ b=-4$
$ c=9$
$ d=13$
Work Step by Step
Two matrices are equal if they have the same dimension and
if corresponding elements, position by position, are equal.
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These matrices have the same dimension, 2$\times$2.
Position by position,
$c-3=6 \quad \Rightarrow \quad c=9$
$a+3=4 \quad \Rightarrow \quad a=1$
$b+2=-2 \quad \Rightarrow \quad b=-4$
$d-4=9 \quad \Rightarrow \quad d=13$
