Calculating Annual salary rate (DHW Exercise10.3)

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Hi :) At age 55 member's salary rate is 85000. To calculate the salary rate at age 56, don't we multiply by $$\frac{\bar{s}_{56}}{\bar{s}_{55}}$$  The DHW solutions use $$\frac{s_{56}}{\bar{s}_{55}}$$ and I don't understand why.