On the number line, a bug A is moving in the positive direction from the point 0, and a bug Bis moving in the negative direction from the point 0. The speeds of both bugs are constant. Both leave 0 at the same time, and three seconds later A has reached 18 and B has reached –15.

When will A and B be 220 units apart?

20 seconds

Step-by-step explanation:

The speed of A is:

sA = 18 units / 3 seconds = 6 units/second

The speed of B is:

sB = -15 units / 3 seconds = -5 units/second

The relative speed is:

s = sA − sB

s = 6 units/second − (-5 units/second)

s = 11 units/second

The time for the distance between them to be 220 units is:

220 units = 11 units/second × t

t = 20 seconds

the answer will be the last one