#### Answer

$a = 4.56$ cm
$b = 4.87$ cm

#### Work Step by Step

Step 1.
Find side $a$.
Side $a$ is the sum of the 1.87 cm-piece and the 2.69 cm-piece.
So
$a = 1.87 cm + 2.69 cm$
$a = 4.56 cm$
Step 2.
Find side $b$.
Side $b$ is the 8.32 cm length minus the 3.45 cm-piece we already know.
So
$b = 8.32 cm - 3.45 cm$
$b = 4.87 cm$