Lin has 13 coins in her pocket that equal 40 cents. All the coins are dimes, d, and pennies, p. Which combination of coins does Lin have? Use the table to answer the question.

To answer this question you should begin with the coin that has a higher value.  If you start with the dime and then just add the correct number of pennies to total $0.40, you will see that you will need 3 dimes ($0.30) and 10 pennies ($0.10).  

I used a guess and check strategy starting with 2 dimes.