Robin has 28 packages of gum and 13 packages of candy. There are 4 pieces in each package. How many pieces of gum does Robin have?
First, we need to find the total number of packages that Robin has. 28 packages of gum and 13 packages of candy is the same as 28 + 13 packages, so we can say that Robin has 41 packages. 

Next, we need to find the total number of pieces in all of the packages. There are 4 pieces in each package, so 4 times 41 packages is the same as 4 x 41 pieces, which is the same as 164 pieces. 

Now, we need to find the number of pieces of gum that Robin has. We know that Robin has 28 packages of gum, and each package has 4 pieces, so we can say that Robin has 28 x 4 pieces of gum, which is the same as 112 pieces of gum. 

Therefore the answer (numeric) is: 

112