Two cellphones received a text message at the same time. both phones blinked as they received the message. one phone blinks every 2 minutes. the other phone blinks every 5 minutes. in how many seconds will they blink together?

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%)