Since the airplane is travelling at a constant height, then your j component stays the same.
Now, you know that the airplane is travelling at a constant velocity. You are given that in 30 seconds, it travels metres. So,
So how far will it have travelled in 70 seconds? This will be your i-component.
Now use that position vector and find its magnitude and angle with respect to the x-axis.
Originally Posted by skeeter
i still have it wrong
it tells me Your answer is within 10% of the correct value. This may be due to roundoff error, or you could have a mistake in your calculation.
Show us what you have done. It should work out.