Solve the following multiplication and addition problems.

The problem is $15 \times 2$.

The top box should contain the final answer.

The visual aid shows 10 and 5 next to $\times 2$, indicating that 15 is split into 10 and 5.

The line with four boxes for multiplication and addition represents the distributive property: $(10 \times 2) + (5 \times 2)$.

Multiply $10 \times 2$ and $5 \times 2$.

The next line shows the sum of these products.

Add the results from the previous step.

The last line shows the final sum.

Now, let's address the first line of blanks: $= \boxed{ } + \boxed{ } \times \boxed{ }$.
Given the subsequent steps, this line is likely meant to show an intermediate calculation where one part of the multiplication is already done.
If $10 \times 2 = 20$, then the expression becomes $20 + (5 \times 2)$.

Here are the filled steps:

The final answer is $\boxed{\text{30}}$.