Carol was sending out birthday invitations to w friends. If each package of invitations she bought had x invitations in it How many packs does she need so that no friend gets left out?
First, we need to find out how many invitations are in total. We know that Carol has w friends, and we know that each package of invitations has x invitations in it. This means that the total number of invitations must be wx. 

Now, we need to find out how many packages of invitations she needs. To do this, we need to divide the total number of invitations by the number of invitations in each package. We know that the total number of invitations is wx, and we know that each package has x invitations in it. This means that Carol needs wx/x packages of invitations. 

However, this is not the final answer, because we need to make sure that Carol has enough invitations for all of her friends. This means that she needs to round up to the nearest whole number. 

The final answer is: 

wx/x = w