Explain the difference between the statements x e x and a cx, where a = {x}

The ratio of rock songs to dance songs on jonathan’s mp3 player is 5: 6. the total number of rock and dance songs jonathan has is between 101 120. how many rock songs does he have?

Awater tank holds 18000 gallons. how long will it take for the water level to reach 6000 gallons if the water is used at anaverage rate of 450 gallons per day

Sawsan recorded the favorite sport of students at her school. she surveyed 200 students. how many students chose tennis?