The original price of a dvd is $9. the sale price is 80% of the original price. what is the sale price of the dvd.

Elena is paid a constant rate for each hour she works. the table shows the amounts of money that elena earned for various amounts of time that she worked.

Me d is also an option but i couldn't get it in the picture

At the movie theatre, child admission is $5.20 and adult admission is $9.70. on sunday three time as many adult tickets as child tickets were sold, for a total sales of $788.90. how many child tickets were sold that day?