I think it's just 2 numbers you add together to get that number. for example number 6 you could add 10 and 5 in the circles to get 15 then you add 15 and 4 to get 19
This is a problem about the general solution of a differential equation.
What we can first do here is separate the variables so that we have the same variable for each side (ex. with the term and with the term).
Then, we can integrate using the power rule to get rid of the differentiating terms, remember to add the constant of integration, C, to at least one side of the resulting equation.
Then here, we just solve for and we have our general solution.
We can see that answer choice D has an equivalent equation, so answer choice D is the correct answer.