the cost of a layer cake is $12.96 plus $3.55 per layer. If Paul has only $30 to spend on a cake, what is the most number of layers he can afford

4 layers with $2.84 left over

Step-by-step explanation:

You start off with the cost of the cake which is $12.96, then add $3.55 (in this case 4 times) until you get the closest number to $30 without going over ($27.16). You find the amount of money that is left over by subtracting you original amount ($30) with the amount you spent total on the cake ($27.16).