Weighted mid after the next event

The best bid is $100$ with a size of $40$ units and the best ask is $101$ with a size of $40$ units. The next event is, with probability $0.5$ each, a market order that removes $10$ units from the ask, or a market order that removes $10$ units from the bid. The weighted mid price is the bid times the ask size, plus the ask times the bid size, all divided by the sum of the sizes. What is the expected weighted mid price after the event? Give a decimal.

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