Answer: 573,948 memberships
Step-by-step explanation:
1. Multiply the number of memberships the year prior by 80%
318,860 * 0.8 = 255088
If they sold 80% more memberships this year, that means you would add 80% of the previous year's memberships (255088) to the number of memberships sold last year (318860).
2. Add 80% of the previous year's memberships to the number of memberships sold last year
255088 + 318860 = 573948