To find the average acceleration of a moving object in the positive x direction that went from velocity 89 m/s to 19 m/s in 7.0 seconds, you need to use the following formula:

```

average acceleration = (final velocity - initial velocity) / time

```

In this case, the final velocity is 19 m/s and the initial velocity is 89 m/s. The time is 7.0 seconds. So, the average acceleration is:

```

average acceleration = (19 m/s - 89 m/s) / 7.0 s

```

```

average acceleration = -10 m/s^2

```

Therefore, the average acceleration of the object is -10 m/s^2 in the positive x direction.