Is f(x) = -1/2 linear?

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

Jackie purchased 3 bottles of water and 2 cups of coffee for a family for $7.35. brian bought 4 bottles of water and 1 cup of coffee for his family for $7.15. how much does each bottle of water cost? how much does each cup of coffee cost? i need this done

Angles r and s are complementary. the measure of angle r is 31 degrees. which equation can be used to find angle s?