What does 2x+1-3=0 means

The mean temperature for the first 4 days in january was 7°c. the mean temperature for the first 5 days in january was 5°c. what was the temperature on the 5th day?

Barbara's piano instructors house is 7 1/8 miles from her house. after biking for 1 3/4 miles she stops to rest how much longer does she need to bike to reach her instructor's house

Me! i really need to get this right before 9. prove the divisibility of 7^6+7^5-7^4 by 11. use factoring so you get a number times 11. just tell me the number. i need this done asap