Final answer:
In a seventh chord in first inversion, the figures are 3-5-6, which signify the intervals of a third, fifth, and sixth above the bass note.
Step-by-step explanation:
The numbers that indicate a seventh chord in first inversion are based on the intervals above the bottom note of the chord, which in first inversion is the third of the chord. A seventh chord contains the root, third, fifth, and seventh degrees of the scale. In root position, the numbers would be 1-3-5-7. When the chord is in first inversion, the third of the chord becomes the bass note, and the intervals above it are now a third, a fifth, and a sixth. Therefore, the figures that represent a seventh chord in first inversion are typically 3-5-6, which show these intervals above the bass note.