(Help!) I don't understand how to do this, could someone help me out?

A circus charges $5 per child ticket and $8 per adult ticket. There were 136 tickets sold for a total of $830. How many child tickets and how many adult tickets were purchased?

Mexico city, mexico, is the world's second largest metropolis and is also one of its fastest-growing cities with a projected growth rate of 3.2% per year. its population in 1991 was 20,899,000 people. use the formula p = 20.899e0.032t to predict its population p in millions with t equal to the number of years after 1991. what is the predicted population to the nearest thousand of mexico city for the year 2010?

Use the data on the dot plot to answer the question.how many people read for more than three hours last week? i'm on a unit test review

Laura read 1/8 of a comic book in 2 days. she reads the same number of pages every day. what part of the book does she read in a week