First-year calculus

Two people drinking coffee. One immediately adds a teaspoon of cream to his. The other waits 5 minutes then adds the cream (which is at a constant temperature). Then they both drink their cofee.

Who has the hotter coffee? Assume that the cream is cooler than the air and use Newton's law of cooling.

Now, I know Newton's law of cooling, but I can't figure out how to solve this one using it (and not just logicing my way through). I mean, how do I start it? Should I assign arbitrary temperatures (ie cream - 60, room-70, coffee - 100) and try to do the math? If so, I'd need to decide on how much coffee is in each cup and then use some physics to calculate how much the coffee is affected by a teaspoon of cream... Which seems ridiculous considering I don't think my professor would want us to do that for our calc class.

I know that I shouldn't be asking for homework help on the internet, but this isn't really a homework problem and it's been bugging me. I just can't think of the proper way to approach it...

No need to do any calculation.

The energy in the cup at the end is equal to the energy in the cream and tea at the start, minus energy lost to surroundings.

Which scenario loses more heat to the surroundings? Clearly the one that started out hotter. (calculate it if you have to, trivial)

So adding the cream first cools it faster.