Rebecca wants to split a collection of marbles into groups of w. Rebecca has x eggs and y marbles. How many groups will be created?
First, Rebecca wants to split a collection of marbles into groups of w. This means that each group will have w marbles in it. 

Second, Rebecca has x eggs and y marbles. This means that she has a total of x + y items. 

Third, we need to find out how many groups will be created. To do this, we need to divide the total number of items by the number of items in each group. This gives us the equation: 

(x + y) / w = z

where z is the number of groups. 

We can solve for z by multiplying both sides of the equation by w: 

x + y = wz

Thus, the number of groups is equal to the sum of the eggs and marbles divided by the number of items in each group.