This section of mathematics is called operations with fractions using division. This means we are taking something and breaking it into pieces. 

Let's read the problem again and unpack what it actually means mathematically. 

What does the following mean mathematically: 

"Errol uses 1/3 can of wet dog food for his dog, Muddy, everyday"

Each day Errol feeds his dog `1/3`  can everyday, therefore it takes him 3 days to finish one can. If it takes him 3 days to finish a can, it also means that one can has 3 servings. Lets express this mathematically:

`1/3 + 1/3 + 1/3 = 1 `

How can we determine the servings in one can? We simple divide the one can by the amount we use each day from the can: 

Number of servings = (number of cans)/(fraction of can used per day)

We know that each day 1/3 of a can is used and it provides 3 servings, lets prove this using the formula above:

 Number of servings =   ` 1/ (1/3)`

Number of servings = `1 * (3/1)`   (reciprocal division law)

Number of servings = 3

Now let's using the formula to answer our question: 

Number of servings = `5 / (1/3)`

Number of servings = `5* (3/1)`  

Number of servings = `15`

Therefore the number of servings is 15

Errol uses 1/3 of a can of dog food per day, which means he uses an entire can in three days' time. That means he gets three servings per can. If he has five cans, he will get 15 servings because 3 multiplied by 5 is 15. To draw it out:

Day1 plus Day 2 plus Day 3 = 1 can used

Day 4 plus Day 5 plus Day 6 = 2 cans used

Day 7 plus Day 8 plus Day 9 = 3 cans used

Day 10 plus Day 11 Plus Day 12= 4 cans used

Day 13 plus Day 14 plus Day 15 = 5 cans used