The cost of 2 bunches of roses and 5 bunches of
carnations is £45.
The cost of 3 bunches of
roses and 4 bunches of
carnations is £50.
Find the cost of one bunch of each

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%)