The answer is X.
In order for it to be a function, there should be only one y-value for every x-value. Graph x is the only one that obeys this rule, therefore it is the answer
10 km in .5 hour. Since it is the same as 20 km in 1 hour. Multiplied by 2.
20 is greater than 15.
Please mark as best!
#4 is 47, 48, 49
47+48+49=144