Quantitative Methods - Ques

A stock is priced at $100.00 and follows a one-period binomial process with an up move that equals 1.05 and a down move that equals 0.97. If 1 million Bernoulli trials are conducted, and the average terminal stock price is $102.00, the probability of an up move (p ) is closest to:

Why does pUp(105) + pDown(97) = 102?

I can’t seem to get my head wrapped around why is it = 102…

Because they stipulated that it’s 102.

That’s the only reason.