Kendra tracks the different species of birds they spot on their birdwatching trip. On Monday they visited 5 sites and saw an average of 7 birds at each site. On Tuesday, Kendra visited 5 sites and saw an average of 5 birds at each site. On Wednesday visited 10 sites and saw an average of 8 birds at each site. On average, how many different birds did Kendra see on each site?
Give me a detailed solution.