21 first-graders and 54 other students attended a school assembly. What percentage of the students at the assembly were first-graders?'

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%)

Zach spent 2/3 hour reading on friday a 11/3 hlurs reading on saturday. how much more time did he read on saturday tha on friday

The population of a bacteria colony grows by a consistent percentage each hour and can be modeled by the function y = 500(1.16)t. what does the value 500 represent in the function?