The question made is How much did I have? This question is about the amount of money that you had before receiving the money from your mom, dad and aunt and uncle. This means that the answer is the $3 you had plus the other $7 you said you had. So, $3+$7=$10. You had $10.
The surface area of the triangular prism that will be covered with insulation is equal to the area of the two triangular faces plus the two lateral rectangular faces