In a movie theater, there are children and adults in the ratio 4:7. If there are 21 adults, how many people total are there in the theater?

Need ! discuss how to convert the standard form of the equation of a circle to the general form. 50 points

Dylan and dusty plan to take weekly surfing lessons together. if the 2-hour lessons are $20 per person and they plan to spend $100 each on new surfboards, what is the maximum number of lessons the two can take if the total amount spent for lessons and surfboards is at most $480?

What is the missing step in this proof ?