Beth bought 35¢ stamps and 15¢ stamps at the post office. If she purchased 60 stamps at a cost of $17, how many of each kind did she buy?

Astudent must have an average on five test that is greater than it equal to 80% but less than 90% to receive a final grade of b. devon's greades on the first four test were 78% 62% 91% and 80% what range if grades on the fifth test would give him a b in the course? ( assuming the highest grade is 100%)