To calculate Marie's cost, we need to determine the amount her employer covers and subtract it from the total premium. Marie's employer covers 50% of the premium, which is $300 per quarter. So the employer contribution is $300 x 0.50 = $150 per quarter.
To find Marie's cost, we subtract the employer contribution from the total premium: $300 - $150 = $150 per quarter. Therefore, Marie's cost is $150.