How much uber take? – Uber - Driver: Drive & Deliver Review

In my ride I pick up rider and drop off. They charge rider $30 and give me only $19.26. Including toll of $2.65. I thought uber take only 25% I.e (30-2.65)X 25% =6.84(toll subtracted) Actually they are taking (30-2.65)X 29.579 = 8.09 Can anybody explain me why? It is not about money only it is about how much they dominate drivers.
Review by better to drive lyft on Uber - Driver: Drive & Deliver.