Parallelogram ABCD: Finding Side Length BC with 35cm Perimeter

To solve this problem, we'll follow these steps:

• Step 1: Identify the given information
• Step 2: Apply the appropriate formula
• Step 3: Perform the necessary calculations

Now, let's work through each step:
Step 1: The problem gives us that the parallelogram has a total perimeter of 35 cm and one side $AB = 9.5$ cm.
Step 2: We'll use the formula for the perimeter of a parallelogram: $P = 2(a + b)$, where $a$ and $b$ are adjacent sides. Here, given that $AB = 9.5$ cm, we have $a = 9.5$ cm.
Step 3: Substitute the known values into the formula:
$35 = 2(9.5 + b)$
Divide both sides by 2:
$17.5 = 9.5 + b$
Solve for $b$:
$b = 17.5 - 9.5 = 8$

Therefore, the length of side $BC$ is $\mathbf{8}$ cm.