Calculate ac if the perimeter of abc is 83 inches

Since you already know BC is 23inches, you can minus it from 83 inches first.
Next, you have to realise that since angle ABC and angle ACB are both 65 degrees and equal, the triangle is an isosceles triangle it means that AC is equals to BC.
Thus, it means that you can divide (83-23) by 2, which is 30 inches