Question

Question was provided via image upload.

Explanation:

Step1: Analyze second diagram

The left value is $b$, there are 3 $p$s, right value is $y$. So the equation is $b = 3p + y$.

Step2: Analyze third diagram

The left has 6 $p$s, right value is $x$, bottom value is $y$. So the equation is $6p = x + y$.

Step3: Analyze fourth diagram

The left has 4 $p$s, right value is $k$. So the equation is $4p = k$.

Answer:

Second diagram: $b = 3p + y$
Third diagram: $6p = x + y$
Fourth diagram: $4p = k$