convert 31 mi/h to m/s. you may need 1 mi=1609. Answer in units of m/s?

Continuing to post your homework here won't help it get done. You can ask about a certain method... but people notice when you post one question after another. I believe it's actually one of the forum rules.

Multiply the given value (31 mi/hr) by a series of properly arranged "ones" and then cancel the resulting units.

(31 mi/hr) * (1609m/1mi)

Since 1609m and 1 mi are the same length it is a "one", and all you are doing here is changing units.

Now do that for any other units you need to change.

Which grade are you studying?

A plane is flying southwest at 155mi/h . Suddenly there is a wind from west at 45.0 mi/h. What is the plane new velocity with respect to the ground in standard position?

It works best to ask a new question in a new topic.