We can split the given figure in 2 right triangles:
So, in order to get the area of each triangle, we need to find the base, denoted by x in both of them. Since both are right triangles, we can to apply Pythagoresn theorem. By applying this theorem to right hand side triangle, we have

so we have

Then, x is given by

Then, the area of the left triangle is given by

Similarly, the area of the second triangle is given by

Then, the area of the entire figure is the sum of the area of the 2 triangles, that is,

Therefore, the answer is: 330 square inches