F should be -1, 6
E should be -4, 2
D should be -4, 9
5 + 6a + 11b
terms: 5; 6a; 11b
Factors of 5: 1; 5
Factors of 6a: 1; 2; 3; 6; a; 2a; 3a; 6a
Factors of 11b: 1; 11; b; 11b
Since they are moving in opposite directions, this is the same as Amy staying still and Erica biking at 10 meters per second away from her.
To travel 1km = 1000m at 10 meters per second, you need 1000/10 = 100 seconds.
i think the answer is c, hope this helps ;)
