ANSWER
31.3 Ω
Step-by-step explanation
Given:
• The power of the heating device, P = 500 W
,
• The current, I = 4 A
Unknown:
• The resistance of the heating device, R
The power, P, on a resistance R when a current I flows through it is,

Solving for R,

Replace with the known values,

Hence, the resistance of the heating device is 31.3 Ω.