Finding distributions of wealth from utility functions
From what it looks like, you are literally trying to subtract $(2)$ from $(1)$, incorrectly as well (You didn't distribute the minus out correctly.) It is saying to use equations 1 through 2 to solve this problem.

You have to set up a Lagrangian with the maximization problem:

$$\max_{x_1, x_2} \ (x_1 + 1)x_2 \\ \text{s.t.} \ 36 - (x_1 - 4)^2 - (x_2 - 6)^2 = c
$$

So we have

$$\mathcal{L} = (x_1 + 1)x_2 - \lambda[36 - (x_1 - 4)^2 - (x_2 - 6)^2 - c]$$

and you should be able to move from there.