Final answer:
An expression that represents the number of pennies in Obesidad's coin collection, where he has 4 times as many pennies as nickels, can be written as 4n, with n representing the number of nickels.
Step-by-step explanation:
The question is asking us to write an expression that represents the relationship between the number of pennies and nickels in Obesidad's coin collection. To address this problem, we can let the variable n represent the number of nickels. Since Obesidad has 4 times as many pennies as nickels, we can write the expression for the number of pennies as 4n. This means that for every nickel Obesidad has, there are four pennies.