How do i solve 7x-y=21

Which triangles area would be calculated using the trigonometric area formula

At 6 1/2 cents per pound of string beans how much does 7 pounds cost

Bella want to know what the students at her school think of her show. which is the best group to survey to find this information a. go to the mall and ask all of the students she recognizes from school b. ask her viewers to call in durning an episode of the show c. get a list of students at her school from the office and use a random number generator to pick 30 of them d. get a list of students at her school from the office and pick the first 30 students on the list