You can find the following formulas in the learning objectives of General Navigation (061):

• Rate of descent (ft/min) = Glide path (degrees) x Ground speed (NM/min) x 100
• Rate of descent (ft/min) = Glide path (%) x Ground speed (kt)

As the True Airspeed is 110 knots and there's a 15-knot tailwind component, the resulting Ground Speed can be calculated as follows:

Ground Speed = True Airspeed + Tailwind Component
Ground Speed = 110 knots + 15 knots Ground Speed = 125 knots

Converting Ground Speed to nautical miles per minute:

Ground Speed in NM/min = 125 knots / 60
Ground Speed in NM/min ≈ 2.08 NM/min

Given the Ground Speed of approximately 2.08 NM/min and a glide path angle of 3.5°, the rate of descent can be calculated as follows:

• Rate of descent (ft/min) = Glide path (degrees) x Ground speed (NM/min) x 100
• Rate of descent (ft/min) = 3.5° × 2.08 NM/min × 100 ft/NM Rate of Descent ≈ 730 ft/min

Alternatively, you can use the following method:

Rate of descent = 5 x Ground Speed x (Glide path / 3)
Rate of descent = 5 x 125 x (3.5/3)
Rate of descent = 729.2 ft/min