Marcus spent 2 hours reading, 1 hour play Rocket League, and took a 2 hour nap. What percent of the total time did he read ?

The percentage of how much Marsha spend time reading is 40%. If Marcus spend 2 hour reading, 1 hour playing Rocket League and took a 2 hour of nap, add them all together which gets you 5. Now divide 100 by 5 because the most is 100% everytime and that gives us 20 of each. But Marcus spend 2 hours so you multiply 20 with 2 again which gives you 40 so this means that Marcus spend 40% out of 100% hours reading.

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value