Explanation:
Let n be the number of nickels that Casey has.
We are told that Megan has 4 times as many nickels as Casey has, therefore, the number of nickels that Megan has will be 4*n.
Now we will add the amounts of nickels that Casey and Megan have to find the total amount of nickels.

Therefore, the expression
will represent the total number of nickels that Casey and Megan have .
Upon combining like terms we will get,


Therefore, Casey and Megan have 5n nickels.