Answer:
Note: <em>The options attached belongs to another question, so the answer is not included</em>
Premium liability at December 31, 2020 = ((510,000*60%) - $130,000) / 8*3
Premium liability at December 31, 2020 = 176,000 / 24
Premium liability at December 31, 2020 = 7,333.33
Premium liability at December 31, 2021 = 7333.33 + ((600000*60%) - 150000) / 8*3
Premium liability at December 31, 2021 = 7333.33 + 360,000 - 150,000
Premium liability at December 31, 2021 = 217,333.33